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• Magento Onepage Success Conversion Tracking Design Pattern

  - by user1734954

  My intent is to track conversions through multiple channels by inserting third party javascript (for example google analytics, optimizely, pricegrabber etc.) into the footer of onepage success . I've accomplished this by adding a block to the footer reference inside of the checkout success node within local.xml and everything works appropriately. My questions are more about efficiency and extensibility. It occurred to me that it would be better to combine all of the blocks into a single block reference and then use a various methods acting on a single call to the various related models to provide the data needed for insertion into the javascript for each of the conversion tracking scripts. Some examples of the common data that conversion tracking may rely on(pseudo): Order ID , Order Total, Order.LineItem.Name(foreach) and so on Currently for each of the scripts I've made a call to the appropriate model passing the customers last order id as the load value and the calling a get() assigning the return value to a variable and then iterating through the data to match the values with the expectations of the given third party service. All of the data should be pulled once when checkout is complete each third party services may expect different data in different formats Here is an example of one of the conversion tracking template files which loads at the footer of checkout success. $order = Mage::getModel('sales/order')->loadByIncrementId(Mage::getSingleton('checkout/session')->getLastRealOrderId()); $amount = number_format($order->getGrandTotal(),2); $customer = Mage::helper('customer')->getCustomer()->getData(); ?> <script type="text/javascript"> popup_email = '<?php echo($customer['email']);?>'; popup_order_number = '<?php echo $this->getOrderId() ?>'; </script> <!-- PriceGrabber Merchant Evaluation Code --> <script type="text/javascript" charset="UTF-8" src="https://www.pricegrabber.com/rating_merchrevpopjs.php?retid=<something>"></script> <noscript><a href="http://www.pricegrabber.com/rating_merchrev.php?retid=<something>" target=_blank> <img src="https://images.pricegrabber.com/images/mr_noprize.jpg" border="0" width="272" height="238" alt="Merchant Evaluation"></a></noscript> <!-- End PriceGrabber Code --> Having just a single piece of code like this is not that big of a deal, but we are doing similar things with a number of different third party services. Pricegrabber is one of the simpler examples. A more sophisticated tracking service expects a comma separated list of all of the product names, ids, prices, categories , order id etc. I would like to make it all more manageable so my idea to do the following: combine all of the template files into a single file Develop a helper class or library to deliver the data to the conversion template Goals Include Extensibility Minimal Model Calls Minimal Method Calls The Questions 1. Is a Mage helper the best route to take? 2. Is there any design pattern you may recommend for the "helper" class? 3. Why would this the design pattern you've chosen be best for this instance?

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• can a python script know that another instance of the same script is running... and then talk to it?

  - by Justin Grant

  I'd like to prevent multiple instances of the same long-running python command-line script from running at the same time, and I'd like the new instance to be able to send data to the original insance before the new instance commits suicide. How can I do this in a cross-platform way? Specifically, I'd like to enable the following behavior: "foo.py" is launched from the command line, and it will stay running for a long time-- days or weeks until the machine is rebooted or the parent process kills it. every few minutes the same script is launched again, but with different command-line parameters when launched, the script should see if any other instances are running. if other instances are running, then instance #2 should send its command-line parameters to instance #1, and then instance #2 should exit. instance #1, if it receives command-line parameters from another script, should spin up a new thread and (using the command-line parameters sent in the step above) start performing the work that instance #2 was going to perform. So I'm looking for two things: how can a python program know another instance of itself is running, and then how can one python command-line program communicate with another? Making this more complicated, the same script needs to run on both Windows and Linux, so ideally the solution would use only the Python standard library and not any OS-specific calls. Although if I need to have a Windows codepath and an *nix codepath (and a big if statement in my code to choose one or the other), that's OK if a "same code" solution isn't possible. I realize I could probably work out a file-based approach (e.g. instance #1 watches a directory for changes and each instance drops a file into that directory when it wants to do work) but I'm a little concerned about cleaning up those files after a non-graceful machine shutdown. I'd ideally be able to use an in-memory solution. But again I'm flexible, if a persistent-file-based approach is the only way to do it, I'm open to that option. More details: I'm trying to do this because our servers are using a monitoring tool which supports running python scripts to collect monitoring data (e.g. results of a database query or web service call) which the monitoring tool then indexes for later use. Some of these scripts are very expensive to start up but cheap to run after startup (e.g. making a DB connection vs. running a query). So we've chosen to keep them running in an infinite loop until the parent process kills them. This works great, but on larger servers 100 instances of the same script may be running, even if they're only gathering data every 20 minutes each. This wreaks havoc with RAM, DB connection limits, etc. We want to switch from 100 processes with 1 thread to one process with 100 threads, each executing the work that, previously, one script was doing. But changing how the scripts are invoked by the monitoring tool is not possible. We need to keep invocation the same (launch a process with different command-line parameters) but but change the scripts to recognize that another one is active, and have the "new" script send its work instructions (from the command line params) over to the "old" script.

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• Cutting large XML file into smaller pieces in C#

  - by NDraskovic

  I have a problem that I'm working on for quite some time now. I have an XML file with over 50000 records (one record has 3 levels). This file is used by one of my applications to control document sending (the record holds, among other informations, the type of document that has to be sent to a certain person). So in my application I load the XML file into a XmlDocument, and then by using SelectNodes method, I create a XmlNodeList from which I read the data I want. The process is like this - our worker takes the persons ID card (simple eith barcode) and reads it with barcode reader. When the barcode value has been read, my application finds the person with that ID in the XML file, and stores the type of the document into a string variable. Then the worker takes the document and reads its barcode, and if the value of documents barcode and the value in the value in the string variable match, the application makes a record that document of type xxxxxxxx will be sent to the person with ID yyyyyyyyy. This is very simple code, it works perfectly for now, and this is how it looks: On textBox1_TextChanged event (worker read persons ID): foreach(XmlNode node in NodeList){ if(String.Compare(node.Attributes.GetNamedItem("ID").Value.ToString(),textBox1.Text)==0) { ControlString = node.ChildNode[3].FirstChild.Attributes.GetNamedItem("doctype").Value.ToString(); break; } } textBox2.Focus(); And on textBox2_TextChanged event (worker read the documents barcode): if(String.Compare(textBox2.Text,ControlString)==0) { //Create a record and insert it into a SQL database } My question is - how will my application perform with larger XML files (I was told that the XML file might be up to 500,000 records large), will this approach be valid, or will I need to cut the file into smaller files. If I have to cut it, please give me an idea with some code samples, I've tried to do it like this: Reading entire record and storing it into a string: private void WriteXml(XmlNode record) { tempXML = record.InnerXml; temp = "<" + record.Name + " code=\"" + record.Attributes.GetNamedItem("code").Value + "\">" + Environment.NewLine; temp += tempXML + Environment.NewLine; temp += "</" + record.Name + ">"; SmallerXMLDocument += temp + Environment.NewLine; temp = ""; i++; } tempXML, temp and SmallerXMLDocument are all string variables. And then in button_Click method I load the XML file into a XmlNodeList (again by using XmlDocument.SelectNodes method) and I try to create one big string value that would hold all records like this: foreach(XmlNode node in nodes) { if(String.Compare(node.ChildNode[3].FirstChild.Attributes.GetNamedItem("doctype").Value.ToString(),doctype1)==0) { WriteXML(node); } } My idea was to create a string value (in this case called SmallerXmlDocument), and when I pass trough the entire XML file, to simply copy the value of that string into a new file. This works, but only for files that have up to 2000 records (and my has way more than that). So, if I need to cut the file into smaller pieces, what would be the best way to do it (keep in mind that there could be up to half a million records in a XML file)? Thanks

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• What are the principles of developing web-applications with action-based java frameworks?

  - by Roman

  Background I'm going to develop a new web-application with java. It's not very big or very complex and I have enough time until it'll "officially" start. I have some JSF/Facelets development background (about half a year). And I also have some expirience with JSP+JSTL. In self-educational purpose (and also in order to find the best solution) I want to prototype the new project with one of action-based frameworks. Actually, I will choose between Spring MVC and Stripes. Problem In order to get correct impression about action-based frameworks (in comparison with JSF) I want to be sure that I use them correctly (in bigger or lesser extent). So, here I list some most-frequent tasks (at least for me) and describe how I solve them with JSF. I want to know how they should be solved with action-based framework (or separately with Spring MVC and Stripes if there is any difference for concrete task). Rendering content: I can apply ready-to-use component from standard jsf libraries (core and html) or from 3rd-party libs (like RichFaces). I can combine simple components and I can easily create my own components which are based on standard components. Rendering data (primitive or reference types) in the correct format: Each component allow to specify a converter for transforming data in both ways (to render and to send to the server). Converter is, as usual, a simple class with 2 small methods. Site navigation: I specify a set of navigation-cases in faces-config.xml. Then I specify action-attribute of a link (or a button) which should match one or more of navigation cases. The best match is choosen by JSF. Implementing flow (multiform wizards for example): I'm using JSF 1.2 so I use Apache Orchestra for the flow (conversation) scope. Form processing: I have a pretty standard java-bean (backing bean in JSF terms) with some scope. I 'map' form fields on this bean properties. If everything goes well (no exceptions and validation is passed) then all these properties are set with values from the form fields. Then I can call one method (specified in button's action attribute) to execute some logic and return string which should much one of my navigation cases to go to the next screen. Forms validation: I can create custom validator (or choose from existing) and add it to almost each component. 3rd-party libraries have sets of custom ajax-validators. Standard validators work only after page is submitted. Actually, I don't like how validation in JSF works. Too much magic there. Many standard components (or maybe all of them) have predefined validation and it's impossible to disable it (Maybe not always, but I met many problems with it). Ajax support: many 3rd-party libraries (MyFaces, IceFaces, OpenFaces, AnotherPrefixFaces...) have strong ajax support and it works pretty well. Until you meet a problem. Too much magic there as well. It's very difficult to make it work if it doesn't work but you've done right as it's described in the manual. User-friendly URLs: people say that there are some libraries for that exist. And it can be done with filters as well. But I've never tried. It seems too complex for the first look. Thanks in advance for explaning how these items (or some of them) can be done with action-based framework.

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• MVC: returning multiple results on stream connection to implement HTML5 SSE

  - by eddo

  I am trying to set up a lightweight HTML5 Server-Sent Event implementation on my MVC 4 Web, without using one of the libraries available to implement sockets and similars. The lightweight approach I am trying is: Client side: EventSource (or jquery.eventsource for IE) Server side: long polling with AsynchController (sorry for dropping here the raw test code but just to give an idea) public class HTML5testAsyncController : AsyncController { private static int curIdx = 0; private static BlockingCollection<string> _data = new BlockingCollection<string>(); static HTML5testAsyncController() { addItems(10); } //adds some test messages static void addItems(int howMany) { _data.Add("started"); for (int i = 0; i < howMany; i++) { _data.Add("HTML5 item" + (curIdx++).ToString()); } _data.Add("ended"); } // here comes the async action, 'Simple' public void SimpleAsync() { AsyncManager.OutstandingOperations.Increment(); Task.Factory.StartNew(() => { var result = string.Empty; var sb = new StringBuilder(); string serializedObject = null; //wait up to 40 secs that a message arrives if (_data.TryTake(out result, TimeSpan.FromMilliseconds(40000))) { JavaScriptSerializer ser = new JavaScriptSerializer(); serializedObject = ser.Serialize(new { item = result, message = "MSG content" }); sb.AppendFormat("data: {0}\n\n", serializedObject); } AsyncManager.Parameters["serializedObject"] = serializedObject; AsyncManager.OutstandingOperations.Decrement(); }); } // callback which returns the results on the stream public ActionResult SimpleCompleted(string serializedObject) { ServerSentEventResult sar = new ServerSentEventResult(); sar.Content = () => { return serializedObject; }; return sar; } //pushes the data on the stream in a format conforming HTML5 SSE public class ServerSentEventResult : ActionResult { public ServerSentEventResult() { } public delegate string GetContent(); public GetContent Content { get; set; } public int Version { get; set; } public override void ExecuteResult(ControllerContext context) { if (context == null) { throw new ArgumentNullException("context"); } if (this.Content != null) { HttpResponseBase response = context.HttpContext.Response; // this is the content type required by chrome 6 for server sent events response.ContentType = "text/event-stream"; response.BufferOutput = false; // this is important because chrome fails with a "failed to load resource" error if the server attempts to put the char set after the content type response.Charset = null; string[] newStrings = context.HttpContext.Request.Headers.GetValues("Last-Event-ID"); if (newStrings == null || newStrings[0] != this.Version.ToString()) { string value = this.Content(); response.Write(string.Format("data:{0}\n\n", value)); //response.Write(string.Format("id:{0}\n", this.Version)); } else { response.Write(""); } } } } } The problem is on the server side as there is still a big gap between the expected result and what's actually going on. Expected result: EventSource opens a stream connection to the server, the server keeps it open for a safe time (say, 2 minutes) so that I am protected from thread leaking from dead clients, as new message events are received by the server (and enqueued to a thread safe collection such as BlockingCollection) they are pushed in the open stream to the client: message 1 received at T+0ms, pushed to the client at T+x message 2 received at T+200ms, pushed to the client at T+x+200ms Actual behaviour: EventSource opens a stream connection to the server, the server keeps it open until a message event arrives (thanks to long polling) once a message is received, MVC pushes the message and closes the connection. EventSource has to reopen the connection and this happens after a couple of seconds. message 1 received at T+0ms, pushed to the client at T+x message 2 received at T+200ms, pushed to the client at T+x+3200ms This is not OK as it defeats the purpose of using SSE as the clients start again reconnecting as in normal polling and message delivery gets delayed. Now, the question: is there a native way to keep the connection open after sending the first message and sending further messages on the same connection?

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• How to develop an english .com domain value rating algorithm?

  - by Tom

  I've been thinking about an algorithm that should rougly be able to guess the value of an english .com domain in most cases. For this to work I want to perform tests that consider the strengths and weaknesses of an english .com domain. A simple point based system is what I had in mind, where each domain property can be given a certain weight to factor it's importance in. I had these properties in mind: domain character length Eg. initially 20 points are added. If the domain has 4 or less characters, no points are substracted. For each extra character, one or more points are substracted on an exponential basis (the more characters, the higher the penalty). domain characters Eg. initially 20 points are added. If the domain is only alphabetic, no points are substracted. For each non-alhabetic character, X points are substracted (exponential increase again). domain name words Scans through a big offline english database, including non-formal speech, eg. words like "tweet" should be recognized. Question 1 : where can I get a modern list of english words for use in such application? Are these lists available for free? Are there lists like these with non-formal words? The more words are found per character, the more points are added. So, a domain with a lot of characters will still not get a lot of points. words hype-level I believe this is a tricky one, but this should be the cause to differentiate perfect but boring domains from perfect and interesting domains. For example, the following domain is probably not that valueable: www.peanutgalaxy.com The algorithm should identify that peanuts and galaxies are not very popular topics on the web. This is just an example. On the other side, a domain like www.shopdeals.com should ring a bell to the hype test, as shops and deals are quite popular on the web. My initial thought would be to see how often these keywords are references to on the web, preferably with some database. Question 2: is this logic flawed, or does this hype level test have merit? Question 3: are such "hype databases" available? Or is there anything else that could work offline? The problem with eg. a query to google is that it requires a lot of requests due to the many domains to be tested. domain name spelling mistakes Domains like "freemoneyz.com" etc. are generally (notice I am making a lot of assumptions in this post but that's necessary I believe) not valueable due to the spelling mistakes. Question 4: are there any offline APIs available to check for spelling mistakes, preferably in javascript or some database that I can use interact with myself. Or should a word list help here as well? use of consonants, vowels etc. A domain that is easy to pronounce (eg. Google) is usually much more valueable than one that is not (eg. Gkyld). Question 5: how does one test for such pronuncability? Do you check for consonants, vowels, etc.? What does a valueable domain have? Has there been any work in this field, where should I look? That is what I came up with, which leads me to my final two questions. Question 6: can you think of any more english .com domain strengths or weaknesses? Which? How would you implement these? Question 7: do you believe this idea has any merit or all, or am I too naive? Anything I should know, read or hear about? Suggestions/comments? Thanks!

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• Help to argue why to develop software on a physical computer rather than via a remote desktop

  - by s5804

  Remote desktops are great and many times a blessing and cost effective (instead of leasing expensive cables). I am not arguing against remote desktops, just if one have the alternative to use either remote desktop or physical computer, I would choose the later. Also note that I am not arguing for or against remote work practices. But in my case I am required to be physically present in the office when developing software. Background, I work in a company which main business is not to develop software. Therefore the company IT policies are mainly focused on security and to efficiently deploying/maintaing thousands of computer to users. Further, the typical employee runs typical Office applications, like a word processors. Because safety/stability is such a big priority, every non production system/application, shall be deployed into a physical different network, called the test network. Software development of course also belongs in the test network. To access the test network the company has created a standard policy, which dictates that access to the test network shall go only via a remote desktop client. Practically from ones production computer one would open up a remote desktop client to a virtual computer located in the test network. On the virtual computer's remote desktop one would be able to access/run/install all development tools, like Eclipse IDE. Another solution would be to have a dedicated physical computer, which is physically only connected to the test network. Both solutions are available in the company. I have tested both approaches and found running Eclipse IDE, SQL developer, in the remote desktop client to be sluggish (keyboard strokes are delayed), commands like alt-tab takes me out of the remote client, enjoying... Further, screen resolution and colors are different, just to mention a few. Therefore there is nothing technical wrong with the remote client, just not optimal and frankly de-motivating. Now with the new policies put in place, plans are to remove the physical computers connected to the test network. I am looking for help to argue for why software developers shall have a dedicated physical software development computer, to be productive and cost effective. Remember that we are physically in office. Further one can notice that we are talking about approx. 50 computers out of 2000 employees. Therefore the extra budget is relatively small. This is more about policy than cost. Please note that there are lots of similar setups in other companies that work great due to a perfectly tuned systems. However, in my case it is sluggish and it would cost more money to trouble shoot the performance and fine tune it rather than to have a few physical computers. As a business case we have argued that productivity will go down by 25%, however it's my feeling that the reality is probably closer to 50%. This business case isn't really accepted and I find it very difficult to defend it to managers that has never ever used a rich IDE in their life, never mind developed software. Further the test network and remote client has no guaranteed service level, therefore it is down for a few hours per month with the lowest priority on the fix list. Help is appreciated.

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• Need help to properly remove duplicates in NHibernate

  - by Michael D. Kirkpatrick

  Here is the problem I am having. I have a database with over 100 records in it. I am paging through the data to get 9 results at a time. When I added a check to see if items are active, it caused the results to start doubling up. A little background: "Product" is the actual product line "ProductSkus" are the actual products that exist in the product line When there is more then 1 ProductSku within Product, it causes a duplicate entry to be returned. See the NHibernate Query below: result = this.Session.CreateCriteria<Model.Product>() .Add(Expression.Eq("IsActive", true)) .AddOrder(new Order("Name", true)) .SetFirstResult(indexNumber).SetMaxResults(maxNumber) // This part of the query duplicates the products .CreateAlias("ProductSkus", "ProdSkus", JoinType.InnerJoin) .Add(Expression.Eq("ProdSkus.IsActive", true)) .CreateAlias("ProductToSubcategory", "ProdToSubcat") .CreateAlias("ProdToSubcat.ProductSubcategory", "ProdSubcat") .Add(Expression.Eq("ProdSubcat.ID", subCatId)) // This part takes out the duplicate products - Removes too many items... // Turns out that with .SetFirstResult(indexNumber).SetMaxResults(maxNumber) // it gets 9 records back then the duplicates are removed. // Example: // Total Records over 100 // Max = 9 // 4 Duplicates removed // Yields 5 records when there should be 9 // Why??? This line is ran in NHibernate on the data after it has been extracted from the SQL server. .SetResultTransformer(new NHibernate.Transform.DistinctRootEntityResultTransformer()) .List<Model.Product>(); I added the DistinctRootEntityResultTransformer to clean up the duplicates. The problem is that it pulls 9 records back that contains duplicates. DistinctRootEntityResultTransformer then cleans up the duplicates in the 9 records. I am basically needing a distinct statement to be ran on the SQL server to begin with. However, distinct on SQL is not going to work since NHibernate by default wants to add every field from every table in the select part of the statement. I am only using the fields that belong to the root table to begin with (Model.Product). If I can tell NHibernate to not add the fields to the joined tables into the select part of the statement along with adding Distinct, it would work. I use NHibernare Profiler to see the actual query: SELECT top 9 this_.ID as ID351_3_, this_.Name as Name351_3_, this_.Description as Descript3_351_3_, this_.IsActive as IsActive351_3_, this_.ManufacturerID as Manufact5_351_3_, prodskus1_.ID as ID373_0_, prodskus1_.Description as Descript2_373_0_, prodskus1_.PartNumber as PartNumber373_0_, prodskus1_.Price as Price373_0_, prodskus1_.IsKit as IsKit373_0_, prodskus1_.IsActive as IsActive373_0_, prodskus1_.IsFeaturedProduct as IsFeatur7_373_0_, prodskus1_.DateAdded as DateAdded373_0_, prodskus1_.Weight as Weight373_0_, prodskus1_.TimesViewed as TimesVi10_373_0_, prodskus1_.TimesOrdered as TimesOr11_373_0_, prodskus1_.ProductID as ProductID373_0_, prodskus1_.OverSizedBoxID as OverSiz13_373_0_, prodtosubc2_.ID as ID362_1_, prodtosubc2_.MasterSubcategory as MasterSu2_362_1_, prodtosubc2_.ProductID as ProductID362_1_, prodtosubc2_.ProductSubcategoryID as ProductS4_362_1_, prodsubcat3_.ID as ID352_2_, prodsubcat3_.Name as Name352_2_, prodsubcat3_.ProductCategoryID as ProductC3_352_2_, prodsubcat3_.ImageID as ImageID352_2_, prodsubcat3_.TriggerShow as TriggerS5_352_2_ FROM Product this_ inner join ProductSku prodskus1_ on this_.ID = prodskus1_.ProductID and (prodskus1_.IsActive = 1) inner join ProductToSubcategory prodtosubc2_ on this_.ID = prodtosubc2_.ProductID inner join ProductSubcategory prodsubcat3_ on prodtosubc2_.ProductSubcategoryID = prodsubcat3_.ID WHERE this_.IsActive = 1 /* @p0 */ and prodskus1_.IsActive = 1 /* @p1 */ and prodsubcat3_.ID = 3 /* @p2 */ ORDER BY this_.Name asc If I hand modify the query and run it directly on the SQL server I get the result set I want (I removed all the extra fields in the select section and added DISTINCT): SELECT DISTINCT top 9 this_.ID as ID351_3_, this_.Name as Name351_3_, this_.Description as Descript3_351_3_, this_.IsActive as IsActive351_3_, this_.ManufacturerID as Manufact5_351_3_, FROM Product this_ inner join ProductSku prodskus1_ on this_.ID = prodskus1_.ProductID and (prodskus1_.IsActive = 1) inner join ProductToSubcategory prodtosubc2_ on this_.ID = prodtosubc2_.ProductID inner join ProductSubcategory prodsubcat3_ on prodtosubc2_.ProductSubcategoryID = prodsubcat3_.ID WHERE this_.IsActive = 1 /* @p0 */ and prodskus1_.IsActive = 1 /* @p1 */ and prodsubcat3_.ID = 3 /* @p2 */ ORDER BY this_.Name asc The big question I now must ask is... What must I change in the NHibernate Query to ultimately get the exact same result? Thanks in advance.

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• Can't get Jacobi algorithm to work in Objective-C

  - by Chris Long

  Hi, For some reason, I can't get this program to work. I've had other CS majors look at it and they can't figure it out either. This program performs the Jacobi algorithm (you can see step-by-step instructions and a MATLAB implementation here). BTW, it's different from the Wikipedia article of the same name. Since NSArray is one-dimensional, I added a method that makes it act like a two-dimensional C array. After running the Jacobi algorithm many times, the diagonal entries in the NSArray (i[0][0], i[1][1], etc.) are supposed to get bigger and the others approach 0. For some reason though, they all increase exponentially. For instance, i[2][4] should equal 0.0000009, not 9999999, while i[2][2] should be big. Thanks in advance, Chris NSArray+Matrix.m @implementation NSArray (Matrix) @dynamic offValue, transposed; - (double)offValue { double sum = 0.0; for ( MatrixItem *item in self ) if ( item.nonDiagonal ) sum += pow( item.value, 2.0 ); return sum; } - (NSMutableArray *)transposed { NSMutableArray *transpose = [[[NSMutableArray alloc] init] autorelease]; int i, j; for ( i = 0; i < 5; i++ ) { for ( j = 0; j < 5; j++ ) { [transpose addObject:[self objectAtRow:j andColumn:i]]; } } return transpose; } - (id)objectAtRow:(NSUInteger)row andColumn:(NSUInteger)column { NSUInteger index = 5 * row + column; return [self objectAtIndex:index]; } - (NSMutableArray *)multiplyWithMatrix:(NSArray *)array { NSMutableArray *result = [[NSMutableArray alloc] init]; int i = 0, j = 0, k = 0; double value; for ( i = 0; i < 5; i++ ) { value = 0.0; for ( j = 0; j < 5; j++ ) { for ( k = 0; k < 5; k++ ) { MatrixItem *firstItem = [self objectAtRow:i andColumn:k]; MatrixItem *secondItem = [array objectAtRow:k andColumn:j]; value += firstItem.value * secondItem.value; } MatrixItem *item = [[MatrixItem alloc] initWithValue:value]; item.row = i; item.column = j; [result addObject:item]; } } return result; } @end Jacobi_AlgorithmAppDelegate.m // ... - (void)jacobiAlgorithmWithEntry:(MatrixItem *)entry { MatrixItem *b11 = [matrix objectAtRow:entry.row andColumn:entry.row]; MatrixItem *b22 = [matrix objectAtRow:entry.column andColumn:entry.column]; double muPlus = ( b22.value + b11.value ) / 2.0; muPlus += sqrt( pow((b22.value - b11.value), 2.0) + 4.0 * pow(entry.value, 2.0) ); Vector *u1 = [[[Vector alloc] initWithX:(-1.0 * entry.value) andY:(b11.value - muPlus)] autorelease]; [u1 normalize]; Vector *u2 = [[[Vector alloc] initWithX:-u1.y andY:u1.x] autorelease]; NSMutableArray *g = [[[NSMutableArray alloc] init] autorelease]; for ( int i = 0; i <= 24; i++ ) { MatrixItem *item = [[[MatrixItem alloc] init] autorelease]; if ( i == 6*entry.row ) item.value = u1.x; else if ( i == 6*entry.column ) item.value = u2.y; else if ( i == ( 5*entry.row + entry.column ) || i == ( 5*entry.column + entry.row ) ) item.value = u1.y; else if ( i % 6 == 0 ) item.value = 1.0; else item.value = 0.0; [g addObject:item]; } NSMutableArray *firstResult = [[g.transposed multiplyWithMatrix:matrix] autorelease]; matrix = [firstResult multiplyWithMatrix:g]; } // ...

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• How can I keep my MVC Views, models, and model binders as clean as possible?

  - by MBonig

  I'm rather new to MVC and as I'm getting into the whole framework more and more I'm finding the modelbinders are becoming tough to maintain. Let me explain... I am writing a basic CRUD-over-database app. My domain models are going to be very rich. In an attempt to keep my controllers as thin as possible I've set it up so that on Create/Edit commands the parameter for the action is a richly populated instance of my domain model. To do this I've implemented a custom model binder. As a result, though, this custom model binder is very specific to the view and the model. I've decided to just override the DefaultModelBinder that ships with MVC 2. In the case where the field being bound to my model is just a textbox (or something as simple), I just delegate to the base method. However, when I'm working with a dropdown or something more complex (the UI dictates that date and time are separate data entry fields but for the model it is one Property), I have to perform some checks and some manual data munging. The end result of this is that I have some pretty tight ties between the View and Binder. I'm architecturally fine with this but from a code maintenance standpoint, it's a nightmare. For example, my model I'm binding here is of type Log (this is the object I will get as a parameter on my Action). The "ServiceStateTime" is a property on Log. The form values of "log.ServiceStartDate" and "log.ServiceStartTime" are totally arbitrary and come from two textboxes on the form (Html.TextBox("log.ServiceStartTime",...)) protected override object GetPropertyValue(ControllerContext controllerContext, ModelBindingContext bindingContext, PropertyDescriptor propertyDescriptor, IModelBinder propertyBinder) { if (propertyDescriptor.Name == "ServiceStartTime") { string date = bindingContext.ValueProvider.GetValue("log.ServiceStartDate").ConvertTo(typeof (string)) as string; string time = bindingContext.ValueProvider.GetValue("log.ServiceStartTime").ConvertTo(typeof (string)) as string; DateTime dateTime = DateTime.Parse(date + " " + time); return dateTime; } if (propertyDescriptor.Name == "ServiceEndTime") { string date = bindingContext.ValueProvider.GetValue("log.ServiceEndDate").ConvertTo(typeof(string)) as string; string time = bindingContext.ValueProvider.GetValue("log.ServiceEndTime").ConvertTo(typeof(string)) as string; DateTime dateTime = DateTime.Parse(date + " " + time); return dateTime; } The Log.ServiceEndTime is a similar field. This doesn't feel very DRY to me. First, if I refactor the ServiceStartTime or ServiceEndTime into different field names, the text strings may get missed (although my refactoring tool of choice, R#, is pretty good at this sort of thing, it wouldn't cause a build-time failure and would only get caught by manual testing). Second, if I decided to arbitrarily change the descriptors "log.ServiceStartDate" and "log.ServiceStartTime", I would run into the same problem. To me, runtime silent errors are the worst kind of error out there. So, I see a couple of options to help here and would love to get some input from people who have come across some of these issues: Refactor any text strings in common between the view and model binders out into const strings attached to the ViewModel object I pass from controller to the aspx/ascx view. This pollutes the ViewModel object, though. Provide unit tests around all of the interactions. I'm a big proponent of unit tests and haven't started fleshing this option out but I've got a gut feeling that it won't save me from foot-shootings. If it matters, the Log and other entities in the system are persisted to the database using Fluent NHibernate. I really want to keep my controllers as thin as possible. So, any suggestions here are greatly welcomed! Thanks

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• Java curious Loop Performance

  - by user1680583

  I have a big problem while evaluate my java code. To simplify the problem I wrote the following code which produce the same curious behavior. Important is the method run() and given double value rate. For my runtime test (in the main method) I set the rate to 0.5 one times and 1.0 the other time. With the value 1.0 the if-statement will be executed in each loop iteration and with the value 0.5 the if-statement will be executed half as much. For this reason I expected longer runtime by the first case but opposite is true. Can anybody explain me this phenomenon?? The result of main: Test mit rate = 0.5 Length: 50000000, IF executions: 25000856 Execution time was 4329 ms. Length: 50000000, IF executions: 24999141 Execution time was 4307 ms. Length: 50000000, IF executions: 25001582 Execution time was 4223 ms. Length: 50000000, IF executions: 25000694 Execution time was 4328 ms. Length: 50000000, IF executions: 25004766 Execution time was 4346 ms. ================================= Test mit rate = 1.0 Length: 50000000, IF executions: 50000000 Execution time was 3482 ms. Length: 50000000, IF executions: 50000000 Execution time was 3572 ms. Length: 50000000, IF executions: 50000000 Execution time was 3529 ms. Length: 50000000, IF executions: 50000000 Execution time was 3479 ms. Length: 50000000, IF executions: 50000000 Execution time was 3473 ms. The Code public ArrayList<Byte> list = new ArrayList<Byte>(); public final int LENGTH = 50000000; public PerformanceTest(){ byte[]arr = new byte[LENGTH]; Random random = new Random(); random.nextBytes(arr); for(byte b : arr) list.add(b); } public void run(double rate){ byte b = 0; int count = 0; for (int i = 0; i < LENGTH; i++) { if(getRate(rate)){ list.set(i, b); count++; } } System.out.println("Length: " + LENGTH + ", IF executions: " + count); } public boolean getRate(double rate){ return Math.random() < rate; } public static void main(String[] args) throws InterruptedException { PerformanceTest test = new PerformanceTest(); long start, end; System.out.println("Test mit rate = 0.5"); for (int i = 0; i < 5; i++) { start=System.currentTimeMillis(); test.run(0.5); end = System.currentTimeMillis(); System.out.println("Execution time was "+(end-start)+" ms."); Thread.sleep(500); } System.out.println("================================="); System.out.println("Test mit rate = 1.0"); for (int i = 0; i < 5; i++) { start=System.currentTimeMillis(); test.run(1.0); end = System.currentTimeMillis(); System.out.println("Execution time was "+(end-start)+" ms."); Thread.sleep(500); } }

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• multi divs centered

  - by user1319385

  I have 2 divs with 3 divs inside them, all 2 wrapped around one big div. I try and center it and its not working. Here is my code: <div stye="margin-left:auto; margin-right:auto; width: 1210px;"> <div id="left" style=" float:left; width: 606px; height: 506px;"> <div style="top:0px; float:left; width:300px; border: 2px solid #FF0; height:502px; text-align:center; font-family: Myriad Pro, Arial, sans-serif; color:#FFF;"><h1>A picture of a cool guy wearing our shirt will go in here.</h1></div> <div style="top:0px; float:left; width:300px; border: 2px solid #FF0; border-left:0px; height:200px; text-align:center; font-family: Myriad Pro, Arial, sans-serif; color:#FFF;"><h1>A product image will go in here.</h1></div> <div style="top:0px; float:left; width:300px; border: 2px solid #FF0;border-top:0px; border-left:0px; height:300px; text-align:center; font-family: Myriad Pro, Arial, sans-serif; color:#FFF;"><h1>A tight product image will go in here.</h1></div> </div> <div id="left" style="float:left; width: 604px; height: 506px;"> <div style="top:0px; float:right; width:300px; border: 2px solid #FF0; border-left:0px; height:502px; text-align:center; font-family: Myriad Pro, Arial, sans-serif; color:#FFF;"><h1>A picture of a cool guy wearing our shirt will go in here.</h1></div> <div style="top:0px; float:left; width:300px; border: 2px solid #FF0; border-left:0px; height:200px; text-align:center; font-family: Myriad Pro, Arial, sans-serif; color:#FFF;"><h1>A product image will go in here.</h1></div> <div style="top:0px; float:left; width:300px; border: 2px solid #FF0;border-top:0px; border-left:0px; height:300px; text-align:center; font-family: Myriad Pro, Arial, sans-serif; color:#FFF;"><h1>A tight product image will go in here.</h1></div> </div> </div>

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• Infinite sharing system (PHP/MySQLi)

  - by Toine Lille

  I'm working on a discount system for whichever customer shares a product and brings in new customers. Each unique visit = $0.05 off, each new customer = $0.50 off (it's a cheap product so yeah, no big numbers). When a new customer shares the site, the customer initially responsible for the new customer (if any) will get half of the new customer's discount as well. The initial customer would get a fourth for the next level and the new customer half of that, etc, creating a tree or pyramid that way that could be infinite. Initial customer ($1.35 discount: 2 new+3 visits + half of 1 new+2 visits) Visitor ($0) Visitor ($0) New customer ($0.60) Visitor ($0) Visitor ($0) Newer customer ($0) New customer ($0) Visitor ($0) The customers are saved along with their IP addresses (bin2hex(inet_pton)) in a database table (customers) with info like a unique id, e-mail address and first date/time the purchased a product (= time of registration). The shares are saved in a separate table within the same database (sharing). Each unique IP addresses that visits the site creates a new row featuring the IP address (also saved as bin2hex(inet_pton)), the id of the customer who shared it and the date/time of the visit. Sharing goes via URL, featuring a GET element containing the customer's id. Visits and new customers overlap, as visits will always occur before the new customer does. That's fine. The date/times are used just to make it a little more secure (I also use the IP along with cookies to see if people cheat the system). If an IP is already in the sharing or customer tables, it does not count and will not create a new entry. Now the problem is, how to make the infinity happen and apply the different values to it? That's all I'd need to know. It needs to calculate the discount for each customer separately, but also allow for monitoring altogether (though that's just a matter of passing all ID's through it). I figured I'd start (after the database connection) with $stmt = $con->prepare('SELECT ip,datetime FROM sharing WHERE sender=?'); $stmt->bind_param('i',$customerid); $stmt->execute(); $stmt->store_result(); $discount = $discount + ($stmt->num_rows * 0.05); $stmt->bind_result($ip,$timeofsharing); to translate all the visits to $0.05 of discount each. To check for the new customers that came from these visits, I wrote the following: while ($sql->fetch()) { $stmt2 = $con->prepare("SELECT datetime FROM users WHERE ip=?"); $stmt2->bind_param('s',$ip); $stmt2->execute(); $stmt2->store_result(); $stmt2->bind_result($timeofpurchase); Followed by a little more security comparing the datetimes: while ($stmt2->fetch()) { if (strtotime($timeofpurchase) < strtotime($timeofsharing)) { $discount = $discount + $0.50; } But this is just for the initial customer's direct results. If I'd want to check for the next level, I'd basically have to put the exact same check and loop in itself, checking each new customer the initial customer they brought to the site, and then for the next level again to check all of the newer customers, etc, etc. What to do? / Where to go? / What would be the correct practice for this? Thanks!

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• How to implement this .NET client and PHP server synchronization scenario?

  - by pbean

  I have a PHP webserver and a .NET mobile application. The .NET application needs data from a database, which is provided (for now) by the php webserver. I'm fairly new to this kind of scenario so I'm not sure what the best practices are. I ran into a couple of problems and I am not certain how to overcome them. For now, I have the following setup. I run a PHP SOAP server which has a couple of operations which simply retrieve data from the database. For this web service I have created a WSDL file. In Visual Studio I added a web reference to my project using the WSDL file and it generated some classes for it. I simply call something like "MyWebService.GetItems();" and I get an array of items in my .NET application, which come straight from the database. Next I also serialize all these retrieved objects to local (permanent) storage. I face a couple of challenges which I don't know how to resolve properly. The idea is for the mobile client to synchronize the data once (at the start of the day), before working, and then use the local storage throughout the day, and synchronize it back at the end of the day. At the moment all data is downloaded through SOAP, and not a subset (only what is needed). How would I know which new information should be sent to the client? Only the server knows what is new, but only the client knows for sure which data it already has. I seem to be doing double work now. The data which is transferred with SOAP basically already are serialized objects. But at the moment I first retrieve all objects through SOAP and the .NET framework automatically deserializes it. Then I serialize all data again myself. It would be more efficient to simply download it to storage, and then deserialize it. The mobile device does not have a lot of memory. In my test data this is not really a problem, but with potentially tenths of thousands of records I can imagine this will become a problem. Currently when I call the SOAP method, it loads all data into memory (as an array) but as described above perhaps it would be better to have it stored into storage directly, and only retrieve from storage the objects that are needed. But how would I store this? An array would serialize to one big XML (or binary) file from which I cannot choose which objects to load. Would I make (possible tenths of thousands) separate files? Also at the end of the day when I want to send the changes back to the server, how would I know which objects to send... since they're not in memory? I hope my troubles are clear and I hope you are able to help me figure out how to implement this the best way. :) Some things are already fixed (like using .NET on the mobile device, using PHP and having a MySQL database server) but other things can most certainly be changed (like using SOAP).

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• C# Object Problem - Can't Solve It

  - by user612041

  I'm getting the error 'Object reference not set to an instance of an object'. I've tried looking at similar problems but genuinely cannot see what the problem is with my program. The line of code that I am having an error with is: labelQuestion.Text = table.Rows[0]["Question"].ToString(); Here is my code in its entirety: using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using System.Data.OleDb; using System.Data.Sql; using System.Data.SqlClient; namespace Quiz_Test { public partial class Form1 : Form { public Form1() { InitializeComponent(); } String chosenAnswer, correctAnswer; DataTable table; private void Form1_Load(object sender, EventArgs e) { //declare connection string using windows security string cnString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\\Users\\Hannah\\Desktop\\QuizQuestions.accdb"; //declare Connection, command and other related objects OleDbConnection conGet = new OleDbConnection(cnString); OleDbCommand cmdGet = new OleDbCommand(); //try //{ //open connection conGet.Open(); //String correctAnswer; cmdGet.CommandType = CommandType.Text; cmdGet.Connection = conGet; cmdGet.CommandText = "SELECT * FROM QuizQuestions ORDER BY rnd()"; OleDbDataReader reader = cmdGet.ExecuteReader(); reader.Read(); labelQuestion.Text = table.Rows[0]["Question"].ToString(); radioButton1.Text = table.Rows[0]["Answer 1"].ToString(); radioButton2.Text = table.Rows[0]["Answer 2"].ToString(); radioButton3.Text = table.Rows[0]["Answer 3"].ToString(); radioButton4.Text = table.Rows[0]["Answer 4"].ToString(); correctAnswer = table.Rows[0]["Correct Answer"].ToString(); ; conGet.Close(); } private void btnSelect_Click(object sender, EventArgs e) { String cnString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\\Users\\Hannah\\Desktop\\QuizQuestions.accdb"; //declare Connection, command and other related objects OleDbConnection conGet = new OleDbConnection(cnString); OleDbCommand cmdGet = new OleDbCommand(); //try { //open connection conGet.Open(); cmdGet.CommandType = CommandType.Text; cmdGet.Connection = conGet; cmdGet.CommandText = "SELECT * FROM QuizQuestions ORDER BY rnd()"; // select all columns in all rows OleDbDataReader reader = cmdGet.ExecuteReader(); reader.Read(); if (radioButton1.Checked) { chosenAnswer = reader["Answer 1"].ToString(); } else if (radioButton2.Checked) { chosenAnswer = reader["Answer 2"].ToString(); } else if (radioButton3.Checked) { chosenAnswer = reader["Answer 3"].ToString(); } else { chosenAnswer = reader["Answer 4"].ToString(); } if (chosenAnswer == reader["Correct Answer"].ToString()) { //chosenCorrectly++; MessageBox.Show("You have got this answer correct"); //label2.Text = "You have got " + chosenCorrectly + " answers correct"; } else { MessageBox.Show("That is not the correct answer"); } } } } } I realise the problem isn't too big but I can't see how my declaration timings are wrong

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• Is it possible to shuffle a 2D matrix while preserving row AND column frequencies?

  - by j_random_hacker

  Suppose I have a 2D array like the following: GACTG AGATA TCCGA Each array element is taken from a small finite set (in my case, DNA nucleotides -- {A, C, G, T}). I would like to randomly shuffle this array somehow while preserving both row and column nucleotide frequencies. Is this possible? Can it be done efficiently? [EDIT]: By this I mean I want to produce a new matrix where each row has the same number of As, Cs, Gs and Ts as the corresponding row of the original matrix, and where each column has the same number of As, Cs, Gs and Ts as the corresponding column of the original matrix. Permuting the rows or columns of the original matrix will not achieve this in general. (E.g. for the example above, the top row has 2 Gs, and 1 each of A, C and T; if this row was swapped with row 2, the top row in the resulting matrix would have 3 As, 1 G and 1 T.) It's simple enough to preserve just column frequencies by shuffling a column at a time, and likewise for rows. But doing this will in general alter the frequencies of the other kind. My thoughts so far: If it's possible to pick 2 rows and 2 columns so that the 4 elements at the corners of this rectangle have the pattern XY YX for some pair of distinct elements X and Y, then replacing these 4 elements with YX XY will maintain both row and column frequencies. In the example at the top, this can be done for (at least) rows 1 and 2 and columns 2 and 5 (whose corners give the 2x2 matrix AG;GA), and for rows 1 and 3 and columns 1 and 4 (whose corners give GT;TG). Clearly this could be repeated a number of times to produce some level of randomisation. Generalising a bit, any "subrectangle" induced by a subset of rows and a subset of columns, in which the frequencies of all rows are the same and the frequencies of all columns are the same, can have both its rows and columns permuted to produce a valid complete rectangle. (Of these, only those subrectangles in which at least 1 element is changed are actually interesting.) Big questions: Are all valid complete matrices reachable by a series of such "subrectangle rearrangements"? I suspect the answer is yes. Are all valid subrectangle rearrangements decomposable into a series of 2x2 swaps? I suspect the answer is no, but I hope it's yes, since that would seem to make it easier to come up with an efficient algorithm. Can some or all of the valid rearrangements be computed efficiently? This question addresses a special case in which the set of possible elements is {0, 1}. The solutions people have come up with there are similar to what I have come up with myself, and are probably usable, but not ideal as they require an arbitrary amount of backtracking to work correctly. Also I'm concerned that only 2x2 swaps are considered. Finally, I would ideally like a solution that can be proven to select a matrix uniformly at random from the set of all matrices having identical row frequencies and column frequencies to the original. I know, I'm asking for a lot :)

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• SQL: Using a CASE Statement to update a 1000 rows at once, how??

  - by SoLoGHoST

  Ok, I would like to use a CASE STATEMENT for this, but I am lost with this. Basically, I need to update a ton of rows, but just on the "position" column. I need to update all "position" values from 0 - count(position) for each id_layout_position column per id_layout column. Here's what I got for a regular update, but I don't wanna throw this into a foreach loop, as it would take forever to do it. I'm using SMF (Simple Machines Forums), so it might look a little different, but the idea is the same, and CASE statements are supported... $smcFunc['db_query']('', ' UPDATE {db_prefix}dp_positions SET position = {int:position} WHERE id_layout_position = {int:id_layout_position} AND id_layout = {int:id_layout}', array( 'position' => $position++, 'id_layout_position' => (int) $id_layout_position, 'id_layout' => (int) $id_layout, ) ); Anyways, I need to apply some sort of CASE on this so that I can auto-increment by 1 all values that it finds and update to the next possible value. I know I'm doing this wrong, even in this QUERY. But I'm totally lost when it comes to CASES. Here's an example of a CASE being used within SMF, so you can see this and hopefully relate: $conditions = ''; foreach ($postgroups as $id => $min_posts) { $conditions .= ' WHEN posts >= ' . $min_posts . (!empty($lastMin) ? ' AND posts <= ' . $lastMin : '') . ' THEN ' . $id; $lastMin = $min_posts; } // A big fat CASE WHEN... END is faster than a zillion UPDATE's ;). $smcFunc['db_query']('', ' UPDATE {db_prefix}members SET id_post_group = CASE ' . $conditions . ' ELSE 0 END' . ($parameter1 != null ? ' WHERE ' . (is_array($parameter1) ? 'id_member IN ({array_int:members})' : 'id_member = {int:members}') : ''), array( 'members' => $parameter1, ) ); Before I do the update, I actually have a SELECT which throws everything I need into arrays like so: $disabled_sections = array(); $positions = array(); while ($row = $smcFunc['db_fetch_assoc']($request)) { if (!isset($disabled_sections[$row['id_group']][$row['id_layout']])) $disabled_sections[$row['id_group']][$row['id_layout']] = array( 'info' => $module_info[$name], 'id_layout_position' => $row['id_layout_position'] ); // Increment the positions... if (!is_null($row['position'])) { if (!isset($positions[$row['id_layout']][$row['id_layout_position']])) $positions[$row['id_layout']][$row['id_layout_position']] = 1; else $positions[$row['id_layout']][$row['id_layout_position']]++; } else $positions[$row['id_layout']][$row['id_layout_position']] = 0; } Thanks, I know if anyone can help me here it's definitely you guys and gals... Anyways, here is my question: How do I use a CASE statement in the first code example, so that I can update all of the rows in the position column from 0 - total # of rows found, that have that id_layout value and that id_layout_position value, and continue this for all different id_layout values in that table? Can I use the arrays above somehow? I'm sure I'll have to use the id_layout and id_layout_position values for this right? But how can I do this?

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• HTML 5 <video> tag vs Flash video. What are the pros and cons?

  - by Vilx-

  Seems like the new <video> tag is all the hype these days, especially since Firefox now supports it. News of this are popping up in blogs all over the place, and everyone seems to be excited. But what about? As much as I searched I could not find anything that would make it better than the good old Flash video. In fact, I see only problems with it: It will still be some time before all the browsers start supporting it, and much more time before most people upgrade; Flash is available already and everyone has it; You can couple Flash with whatever fancy UI you want for controlling the playback. I gather that the tag will be controllable as well (via JavaScript probably), but will it be able to go fullscreen? The only two pros for a <video> tag that I can see are: It is more "semantic" - which probably holds no importance to a whole lot of people, including me; It is not dependent on a single commercial 3rd party entity (Adobe) - which I also don't see as a compelling reason to switch, because free players and video converters are already available, and Adobe is not hindering the whole process in any way (it's not in their interests even). So... what's the big deal? Added: OK, so there is one more Pro... maybe. Support for mobile devices. Hard to say though. A number of thoughts race through my head about the subject: How many mobile devices are actually able to decode video at a decent speed anyway, Flash or otherwise? How long until mainstream mobile devices get the <video> support? Even if it is available through updates, how many people actually do that? How many people watch videos on web pages on their mobile phones at all? As for the semantics part - I understand that search engines might be able to detect videos better now, but... what will they do with them anyway? OK, so they know that there is a video in the page. And? They can't index a video! I'd like some more arguments here. Added: Just thought of another Cons. This opens up a whole new area of cross-browser incompatibility. HTML and CSS is quite messy already in this aspect. Flash at least is the same everywhere. But it's enough for at least one major browser vendor to decide against the <video> tag (can anyone say "Internet Explorer"?) and we have a nice new area of hell to explore. Added: A Pro just came in. More competition = more innovation. That's true. Giving Adobe more competition will probably force them to improve Flash in areas it has been lacking so far. Linux seems to be a weak spot for it, cited by many.

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• Form inside a hidden div has no values on post

  - by Mick

  I have a html form that posts to a new page on submit. If required a user can click a button to make a small table visible in a div box. this adds more text input fields to my form. The problem is, regardless of the div box being hidden or visible none of the additional fields data is sent when the form is posted . the div box code function quotevisi() { document.getElementById("quote").style.visibility = "visible"; tdat = "" ; tdat += "<h2 align='center' >Client Quotation </h2>" ; tdat += "<table align='center'cellpadding='1' width='690px'><tr>" tdat += "<td ></td><td>Additional 1</td>" ; tdat += "<td ><label><textarea id='line1' cols='50' rows='1'>" tdat += "</textarea></label></td></tr>" tdat += "<td ></td><td >Additional 2 </td>" ; tdat += "<td ><label><textarea id='line2' name='line2' cols='50' rows='1'>" tdat += "</textarea></label></td></tr>" tdat += "<td ></td><td >Additional 3 </td>" ; tdat += "<td ><label><textarea id='line3' name='line3' cols='50' rows='1'>" tdat += "</textarea></label></td></tr>" tdat += "<td ></td><td >Special Instructions</td>" ; tdat += "<td ><label><textarea id='special' name='special' cols='50' rows='1'>" tdat += "</textarea></label></td></tr>" tdat += "<td ></td><td ></td> <td>" ; tdat += "<input type='button' value='View Quote' onclick='view_quote()' /> " tdat += "<input type='button' value='Close' onclick='closequote()' /> " tdat += "<td ></td> " ; tdat += "</table> " // display in the quote div (style sheet) document.getElementById('quote').innerHTML= tdat } The form is a bit big to but the button for the hidden field is this <td ><input class="buttn" type="button" value="Extra Quote details " onclick="quotevisi();" /> </td> I would of thought that all this information would go with the form on post . But it doesent. Oh finally the div box code is placed after this line <form style='background-color:ccc' id='form1' name='form1' method='post' action='process.php' > Any help or thoughts would be much appreciated thanks Mick

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• Generating strongly biased radom numbers for tests

  - by nobody

  I want to run tests with randomized inputs and need to generate 'sensible' random numbers, that is, numbers that match good enough to pass the tested function's preconditions, but hopefully wreak havoc deeper inside its code. math.random() (I'm using Lua) produces uniformly distributed random numbers. Scaling these up will give far more big numbers than small numbers, and there will be very few integers. I would like to skew the random numbers (or generate new ones using the old function as a randomness source) in a way that strongly favors 'simple' numbers, but will still cover the whole range, I.e. extending up to positive/negative infinity (or ±1e309 for double). This means: numbers up to, say, ten should be most common, integers should be more common than fractions, numbers ending in 0.5 should be the most common fractions, followed by 0.25 and 0.75; then 0.125, and so on. A different description: Fix a base probability x such that probabilities will sum to one and define the probability of a number n as xk where k is the generation in which n is constructed as a surreal number1. That assigns x to 0, x2 to -1 and +1, x3 to -2, -1/2, +1/2 and +2, and so on. This gives a nice description of something close to what I want (it skews a bit too much), but is near-unusable for computing random numbers. The resulting distribution is nowhere continuous (it's fractal!), I'm not sure how to determine the base probability x (I think for infinite precision it would be zero), and computing numbers based on this by iteration is awfully slow (spending near-infinite time to construct large numbers). Does anyone know of a simple approximation that, given a uniformly distributed randomness source, produces random numbers very roughly distributed as described above? I would like to run thousands of randomized tests, quantity/speed is more important than quality. Still, better numbers mean less inputs get rejected. Lua has a JIT, so performance can't be reasonably predicted. Jumps based on randomness will break every prediction, and many calls to math.random() will be slow, too. This means a closed formula will be better than an iterative or recursive one. 1 Wikipedia has an article on surreal numbers, with a nice picture. A surreal number is a pair of two surreal numbers, i.e. x := {n|m}, and its value is the number in the middle of the pair, i.e. (for finite numbers) {n|m} = (n+m)/2 (as rational). If one side of the pair is empty, that's interpreted as increment (or decrement, if right is empty) by one. If both sides are empty, that's zero. Initially, there are no numbers, so the only number one can build is 0 := { | }. In generation two one can build numbers {0| } =: 1 and { |0} =: -1, in three we get {1| } =: 2, {|1} =: -2, {0|1} =: 1/2 and {-1|0} =: -1/2 (plus some more complex representations of known numbers, e.g. {-1|1} ? 0). Note that e.g. 1/3 is never generated by finite numbers because it is an infinite fraction – the same goes for floats, 1/3 is never represented exactly.

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• Override `drop` for a custom sequence

  - by Bruno Reis

  In short: in Clojure, is there a way to redefine a function from the standard sequence API (which is not defined on any interface like ISeq, IndexedSeq, etc) on a custom sequence type I wrote? 1. Huge data files I have big files in the following format: A long (8 bytes) containing the number n of entries n entries, each one being composed of 3 longs (ie, 24 bytes) 2. Custom sequence I want to have a sequence on these entries. Since I cannot usually hold all the data in memory at once, and I want fast sequential access on it, I wrote a class similar to the following: (deftype DataSeq [id ^long cnt ^long i cached-seq] clojure.lang.IndexedSeq (index [_] i) (count [_] (- cnt i)) (seq [this] this) (first [_] (first cached-seq)) (more [this] (if-let [s (next this)] s '())) (next [_] (if (not= (inc i) cnt) (if (next cached-seq) (DataSeq. id cnt (inc i) (next cached-seq)) (DataSeq. id cnt (inc i) (with-open [f (open-data-file id)] ; open a memory mapped byte array on the file ; seek to the exact position to begin reading ; decide on an optimal amount of data to read ; eagerly read and return that amount of data )))))) The main idea is to read ahead a bunch of entries in a list and then consume from that list. Whenever the cache is completely consumed, if there are remaining entries, they are read from the file in a new cache list. Simple as that. To create an instance of such a sequence, I use a very simple function like: (defn ^DataSeq load-data [id] (next (DataSeq. id (count-entries id) -1 []))) ; count-entries is a trivial "open file and read a long" memoized As you can see, the format of the data allowed me to implement count in very simply and efficiently. 3. drop could be O(1) In the same spirit, I'd like to reimplement drop. The format of these data files allows me to reimplement drop in O(1) (instead of the standard O(n)), as follows: if dropping less then the remaining cached items, just drop the same amount from the cache and done; if dropping more than cnt, then just return the empty list. otherwise, just figure out the position in the data file, jump right into that position, and read data from there. My difficulty is that drop is not implemented in the same way as count, first, seq, etc. The latter functions call a similarly named static method in RT which, in turn, calls my implementation above, while the former, drop, does not check if the instance of the sequence it is being called on provides a custom implementation. Obviously, I could provide a function named anything but drop that does exactly what I want, but that would force other people (including my future self) to remember to use it instead of drop every single time, which sucks. So, the question is: is it possible to override the default behaviour of drop? 4. A workaround (I dislike) While writing this question, I've just figured out a possible workaround: make the reading even lazier. The custom sequence would just keep an index and postpone the reading operation, that would happen only when first was called. The problem is that I'd need some mutable state: the first call to first would cause some data to be read into a cache, all the subsequent calls would return data from this cache. There would be a similar logic on next: if there's a cache, just next it; otherwise, don't bother populating it -- it will be done when first is called again. This would avoid unnecessary disk reads. However, this is still less than optimal -- it is still O(n), and it could easily be O(1). Anyways, I don't like this workaround, and my question is still open. Any thoughts? Thanks.

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• Drop down list in menu disappears before able to click

  - by user1834770

  I've had quite a search through forums looking for a solution for this, but since I don't know coding I'm not sure what applies to me and what doesn't. So, apologies if this is an often solved problem, but I'll greatly appreciate your help! After much trial and error, I've managed to get a drop down list of pages on my navigation bar; however, when I go to click on a sub-page, the entire menu disappears. I've read through other similar problems where there has been an issue with a margin that's too big, but I think my margins are set to '0'. The blog is at: http://swirlstwirlsblog.blogspot.com.au/ I haven't got content in the sub pages but there are there and linked in the html/javascript widget. I've also looked at it in Chrome, Mozilla, and Safari and it's the same issue. I'm also not sure if this is a javascript, css, or html problem, so please be kind in your responses--I'm only new! Thanks so much to anyone able to help me on this. Here's the script I used in the Widget: <ul id="jsddm"> <li><a href="http://swirlstwirlsblog.blogspot.com.au/">Home</a> <li><a href="http://swirlstwirlsblog.blogspot.com.au/search/label/sparkles">Sparkles</a> </li> <li><a href="http://swirlstwirlsblog.blogspot.com.au/search/label/friendship">Friendship</a> </li> <li><a href="http://swirlstwirlsblog.blogspot.com.au/search/label/humour">Humour</a> </li> <li><a href="">About</a> <ul> <li><a href="http://swirlstwirlsblog.blogspot.com.au/p/about_16.html">Us</a></li> <li><a href="http://swirlstwirlsblog.blogspot.com.au/p/contributers.html">Contributors</a> </li> <li><a href="http://swirlstwirlsblog.blogspot.com.au/p/advertising.html">Advertising</a> </li> <li><a href="http://swirlstwirlsblog.blogspot.com.au/p/privacy-policies.html">Privacy</a></li> <li><a href="http://swirlstwirlsblog.blogspot.com.au/p/contact.html">Contact</a></li> </ul> </li> </li></ul> And here's the html code I put in the template: <pre>#jsddm { margin: 0; padding: 15px; z-index:1000000000; position:relative; } #jsddm li { float: left; list-style: none; font: 12px Tahoma, Arial; } #jsddm li a { display: block; white-space: nowrap; margin:1px 3px; padding: 5px 10px; border-right: 1px color: eeeeee; text-shadow: #ffffff 0 1px 0; color: #363636; font-size: 15px; font-family: crushed; text-decoration: none; vertical-align: middle; } #jsddm li a:hover { background: #C8C8C8; } #jsddm li ul { margin: 0; padding: 0; position: absolute; visibility: hidden; border-top: 1px solid white; } #jsddm li ul li { float: none; display: inline; } #jsddm li ul li a { width: auto; background: #ffffff; } #jsddm li ul li a:hover { background: #eeeeee; }</pre>

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• Nested loop traversing arrays

  - by alecco

  There are 2 very big series of elements, the second 100 times bigger than the first. For each element of the first series, there are 0 or more elements on the second series. This can be traversed and processed with 2 nested loops. But the unpredictability of the amount of matching elements for each member of the first array makes things very, very slow. The actual processing of the 2nd series of elements involves logical and (&) and a population count. I couldn't find good optimizations using C but I am considering doing inline asm, doing rep* mov* or similar for each element of the first series and then doing the batch processing of the matching bytes of the second series, perhaps in buffers of 1MB or something. But the code would be get quite messy. Does anybody know of a better way? C preferred but x86 ASM OK too. Many thanks! Sample/demo code with simplified problem, first series are "people" and second series are "events", for clarity's sake. (the original problem is actually 100m and 10,000m entries!) #include <stdio.h> #include <stdint.h> #define PEOPLE 1000000 // 1m struct Person { uint8_t age; // Filtering condition uint8_t cnt; // Number of events for this person in E } P[PEOPLE]; // Each has 0 or more bytes with bit flags #define EVENTS 100000000 // 100m uint8_t P1[EVENTS]; // Property 1 flags uint8_t P2[EVENTS]; // Property 2 flags void init_arrays() { for (int i = 0; i < PEOPLE; i++) { // just some stuff P[i].age = i & 0x07; P[i].cnt = i % 220; // assert( sum < EVENTS ); } for (int i = 0; i < EVENTS; i++) { P1[i] = i % 7; // just some stuff P2[i] = i % 9; // just some other stuff } } int main(int argc, char *argv[]) { uint64_t sum = 0, fcur = 0; int age_filter = 7; // just some init_arrays(); // Init P, P1, P2 for (int64_t p = 0; p < PEOPLE ; p++) if (P[p].age < age_filter) for (int64_t e = 0; e < P[p].cnt ; e++, fcur++) sum += __builtin_popcount( P1[fcur] & P2[fcur] ); else fcur += P[p].cnt; // skip this person's events printf("(dummy %ld %ld)\n", sum, fcur ); return 0; } gcc -O5 -march=native -std=c99 test.c -o test

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• Testing for Adjacent Cells In a Multi-level Grid

  - by Steve

  I'm designing an algorithm to test whether cells on a grid are adjacent or not. The catch is that the cells are not on a flat grid. They are on a multi-level grid such as the one drawn below. Level 1 (Top Level) | - - - - - | | A | B | C | | - - - - - | | D | E | F | | - - - - - | | G | H | I | | - - - - - | Level 2 | -Block A- | -Block B- | | 1 | 2 | 3 | 1 | 2 | 3 | | - - - - - | - - - - - | | 4 | 5 | 6 | 4 | 5 | 6 | ... | - - - - - | - - - - - | | 7 | 8 | 9 | 7 | 8 | 9 | | - - - - - | - - - - - | | -Block D- | -Block E- | | 1 | 2 | 3 | 1 | 2 | 3 | | - - - - - | - - - - - | | 4 | 5 | 6 | 4 | 5 | 6 | ... | - - - - - | - - - - - | | 7 | 8 | 9 | 7 | 8 | 9 | | - - - - - | - - - - - | . . . . . . This diagram is simplified from my actual need but the concept is the same. There is a top level block with many cells within it (level 1). Each block is further subdivided into many more cells (level 2). Those cells are further subdivided into level 3, 4 and 5 for my project but let's just stick to two levels for this question. I'm receiving inputs for my function in the form of "A8, A9, B7, D3". That's a list of cell Ids where each cell Id has the format (level 1 id)(level 2 id). Let's start by comparing just 2 cells, A8 and A9. That's easy because they are in the same block. private static RelativePosition getRelativePositionInTheSameBlock(String v1, String v2) { RelativePosition relativePosition; if( v1-v2 == -1 ) { relativePosition = RelativePosition.LEFT_OF; } else if (v1-v2 == 1) { relativePosition = RelativePosition.RIGHT_OF; } else if (v1-v2 == -BLOCK_WIDTH) { relativePosition = RelativePosition.TOP_OF; } else if (v1-v2 == BLOCK_WIDTH) { relativePosition = RelativePosition.BOTTOM_OF; } else { relativePosition = RelativePosition.NOT_ADJACENT; } return relativePosition; } An A9 - B7 comparison could be done by checking if A is a multiple of BLOCK_WIDTH and whether B is (A-BLOCK_WIDTH+1). Either that or just check naively if the A/B pair is 3-1, 6-4 or 9-7 for better readability. For B7 - D3, they are not adjacent but D3 is adjacent to A9 so I can do a similar adjacency test as above. So getting away from the little details and focusing on the big picture. Is this really the best way to do it? Keeping in mind the following points: I actually have 5 levels not 2, so I could potentially get a list like "A8A1A, A8A1B, B1A2A, B1A2B". Adding a new cell to compare still requires me to compare all the other cells before it (seems like the best I could do for this step is O(n)) The cells aren't all 3x3 blocks, they're just that way for my example. They could be MxN blocks with different M and N for different levels. In my current implementation above, I have separate functions to check adjacency if the cells are in the same blocks, if they are in separate horizontally adjacent blocks or if they are in separate vertically adjacent blocks. That means I have to know the position of the two blocks at the current level before I call one of those functions for the layer below. Judging by the complexity of having to deal with mulitple functions for different edge cases at different levels and having 5 levels of nested if statements. I'm wondering if another design is more suitable. Perhaps a more recursive solution, use of other data structures, or perhaps map the entire multi-level grid to a single-level grid (my quick calculations gives me about 700,000+ atomic cell ids). Even if I go that route, mapping from multi-level to single level is a non-trivial task in itself.

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• XMLNodes being appended to an XMLNode are "undefined"? Actionscript 2.0 is being unkind

  - by DigitalMercenary

  If anyone can offer an explanation for this one, I'd LOVE to see it! I was required to append a legacy application to display 20 random questions from an XML data source, as opposed to the total of 70 questions that are part of the original XML. No big deal, right? WRONG! I got it to work just fine in the end, but it's a total HACK! For some reason, some of the nodes that I am appending to a dynamically generated XML document are being returned as "undefined". I kept getting between 16 and 20 questions to render until I modified my iteration from a 'for' loop to a 'do while' loop with the appropriate number of XMLNodes as the condition of the 'do while' loop. Can anyone offer an explanation? Below is the code, with some notes for the reader : function editXML(xml:XML):XML { var node:XMLNode = xml.firstChild; var newNode:XMLNode = new XMLNode(); var nodeArray:Array = new Array(); var usedNodes:Array = new Array(); var totalNodes:Number = node.lastChild.childNodes.length - 1; var nextNode:Number; var returnNode:XMLNode = new XMLNode(); var tempNode:XMLNode; var buildNode:XMLNode; var addNode:Boolean = true; var tempXML:XML = new XML(); var pagesNode:XMLNode = tempXML.createElement("pages"); tempXML.appendChild(pagesNode); tempXML.appendChild(node.childNodes[0]); tempXML.appendChild(node.childNodes[1]); tempXML.appendChild(node.childNodes[2]); var questionsNode:XMLNode = tempXML.createElement("pages"); tempXML.firstChild.appendChild(questionsNode); do { nextNode = Math.floor(Math.random()*totalNodes); **//random number to represent random node** //trace(nextNode + " nextNode"); **//check usedNodes Array to look for node.childNodes[nextNode]. If it already exists, skip and reloop.** trace(node.childNodes[1].childNodes[nextNode] + " : pre building Node " + totalNodes); if(usedNodes.length == 0) { buildNode = new XMLNode(); buildNode.nodeName = node.childNodes[1].childNodes[nextNode].nodeName; buildNode.nodeValue = node.childNodes[1].childNodes[nextNode].nodeValue; tempXML.firstChild.lastChild.appendChild(node.childNodes[1].childNodes[nextNode]) usedNodes.push(node.childNodes[1].childNodes[nextNode]); nodeArray.push(node.childNodes[1].childNodes[nextNode]); trace("adding first node : " + nodeArray.length); addNode = false; } else { for(var j:Number = 0; j < usedNodes.length; j++) { if(usedNodes[j] == node.childNodes[1].childNodes[nextNode]) { addNode = false; trace("skipping node : " + nodeArray.length); } } } **//if node not in usedNodes, add node to XML** if(addNode) { trace(node.childNodes[1].childNodes[nextNode] + " : building Node"); **//This trace statement produced a valid node** tempXML.firstChild.lastChild.appendChild(node.childNodes[1].childNodes[nextNode]); **//Before modifying the code from adding nodes to the xml from an Array called 'nodeArray' in a for loop to adding nodes directly to the xml in a do while loop with the length of the xml node used to retrieve data for the questions as the condition, I was not always getting 20 questions. Some of the nodes were being rendered as 'undefined' and not appended to the xml, even though they were traced and proven valid before the attemp to append them to the xml was made** usedNodes.push(node.childNodes[1].childNodes[nextNode]); } addNode = true; } while(tempXML.firstChild.lastChild.childNodes.length <= 19); trace(tempXML.firstChild.lastChild.childNodes.length + " final nodes Length"); courseXML = tempXML; //removes the old question list of 70 and replaces it with the new question list of 20. Question list is the last node. return tempXML; } If I had my choice, I would have rebuilt the whole application in Flex with AS3. I didn't have that choice. If anyone can explain this mystery, PLEASE DO! Thank you in advance!

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