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• How to add deploy.jar to classpath?

  - by dma_k

  I am facing the problem: I need to add ${java.home}/lib/deploy.jar JAR file to classpath in the runtime (dynamically from java). The solution with Thread#setContextClassLoader(ClassLoader) (mentioned here) does not work because of this bug (if somebody can explain what is really a problem – you are welcome). The solution with -Xbootclasspath/a:"%JAVA_HOME%/jre/lib/deploy.jar" does not work well for me, because I want to have "pure executable jar" as a deliverable: no wrapping scripts please (more over %JAVA_HOME% may not be defined in user's environment in Windows for example, plus I need to write a script per platform) The solution with merging deploy.jar file into my deliverable works only if I make a build on Windows platform. Unfortunately, when the deliverable is produced on build server running on Linux, I got Linux-dependant JAR, which does not execute on Windows – it fails with the trace below. I have read How the Java Launcher Finds Classes and Java programming dynamics: Java classes and class loading articles but I've got no extra ideas, how to correctly handle this situation. Any advices or solutions are very welcomed. Trace: java.lang.NoClassDefFoundError: Could not initialize class com.sun.deploy.config.Config at com.sun.deploy.net.proxy.UserDefinedProxyConfig.getBrowserProxyInfo(UserDefinedProxyConfig.java:43) at com.sun.deploy.net.proxy.DynamicProxyManager.reset(DynamicProxyManager.java:235) at com.sun.deploy.net.proxy.DeployProxySelector.reset(DeployProxySelector.java:59) ... java.lang.NullPointerException at com.sun.deploy.net.proxy.DynamicProxyManager.getProxyList(DynamicProxyManager.java:63) at com.sun.deploy.net.proxy.DeployProxySelector.select(DeployProxySelector.java:166)

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• Creating WPF components in background thread

  - by mizipzor

  Im working on a reporting system, a series of DocumentPage are to be created through a DocumentPaginator. These documents include a number of WPF components that are to be instantiated so the paginator includes the correct things when later sent to the XpsDocumentWriter (which in turn is sent to the actual printer). My problem now is that the DocumentPage instances take quite a while to create (enough for Windows to mark the application as frozen) so I tried to create them in a background thread, which is problematic since WPF expects the attributes on them to be set from the GUI thread. I would also like to have a progress bar showing up, indicating how many pages have been created so far. Thus, it looks like Im trying to get two things to happen in parallell on the GUI. The problem is hard to explain and Im really not sure how to tackle it. In short: Create a series of DocumentPage's. These include WPF components These are to be created on a background thread, or use some other trick so the application isnt frozen. After each page is created, a WPF ProgressBar should be updated. If there is no decent way to do this, alternate solutions and approaches are more than welcome.

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• css layout for footer at bottom with dynamic ajax content changing height of page

  - by m42

  [Update] I actually compromised on this problem for now by foregoing the fixed footer design. It seems that there is no problem with dynamic content moving the footer and resizing containers appropriately unless the footer is fixed to the browser bottom initially. I hope others will eventually provide a great solution that encompasses the best of both worlds. I spent all day trying to get the footer to move down the page to accommodate dynamically added (via ajax) content. I really need some pointers or links because I haven't found anything that helps. Basically: My site has some pages that begin with only a text box and a button so that the total height of the content area is only a few inches beneath the header area. I don't have any problem getting the sticky footer working so that the footer appears at the bottom of the browser window even when there is very little content on screen. That same css layout works fine for other pages that have content that extends beneath the browser window. The catch: The content has to be rendered and passed to the browser with the initial load. The Problem: Any content that is added to the page via AJAX after the initial load paints down the page correctly -- but the footer remains in its initial location. Please tell me there is a fix for this. I can't post the css until checking with my boss first - if possible - and if needed, I will later - but it's just a very basic version of the many sticky footer css solutions floating around the web. Thanks.

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• A potentially dangerous Request.Form value was detected: Dealing with these errors proactively, or a

  - by Albert

  I'm noticing this error more and more in my error logs. I've read through the questions here talking about this error, but they don't address what I would like to do (see below). I'm considering three options, in the order of preference: 1) When submitting a form (I use formviews almost exclusively, if that helps), if potentially dangerous characters are detected, automatically strip them out and submit. 2) When submitting a form, if potentially dangerous characters are detected, alert the user and let them fix it before trying again. 3) After the exception is generated, deal with it and alert the user. I'm hoping one of the first two options might be able to do somewhat globally...I know for the 3rd I'd have to alter a TON of Try-Catch blocks I already have in place. Doable, but labor intensive. I'd rather be proactive about it if at all possible and avoid the exception all together. Perhaps one approach to #1 would be to write a block of code that could loop through all text entry fields in a formview, during the insert/update event, and strip the characters out. I'm ok with that, but I'd rather not have to heavily alter all my Insert/Update events to accomplish this. Or maybe I just create a different class to do the text checking/deleting, and only insert 1 line of code in each Insert/Update event. If anyone can come up with some example code of any of these approaches that would be a help. Thanks for any ideas or information. I'm definitely open to other solutions too; these are only the 3 that came to mind. I can say that I don't want to turn request validation off though.

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• Compact data structure for storing a large set of integral values

  - by Odrade

  I'm working on an application that needs to pass around large sets of Int32 values. The sets are expected to contain ~1,000,000-50,000,000 items, where each item is a database key in the range 0-50,000,000. I expect distribution of ids in any given set to be effectively random over this range. The operations I need on the set are dirt simple: Add a new value Iterate over all of the values. There is a serious concern about the memory usage of these sets, so I'm looking for a data structure that can store the ids more efficiently than a simple List<int>or HashSet<int>. I've looked at BitArray, but that can be wasteful depending on how sparse the ids are. I've also considered a bitwise trie, but I'm unsure how to calculate the space efficiency of that solution for the expected data. A Bloom Filter would be great, if only I could tolerate the false negatives. I would appreciate any suggestions of data structures suitable for this purpose. I'm interested in both out-of-the-box and custom solutions. EDIT: To answer your questions: No, the items don't need to be sorted By "pass around" I mean both pass between methods and serialize and send over the wire. I clearly should have mentioned this. There could be a decent number of these sets in memory at once (~100).

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• Function pointers in Objective-C

  - by Stefan Klumpp

  I have the following scenario: Class_A - method_U - method_V - method_X - method_Y Class_B - method_M - method_N HttpClass - startRequest - didReceiveResponse // is a callback Now I want to realize these three flows (actually there are many more, but these are enough to demonstrate my question): Class_A :: method_X -> HttpClass :: startRequest:params -> ... wait, wait, wait ... -> HttpClass :: didReceiveResponse -> Class_A :: method_Y:result and: Class_A :: method_U -> HttpClass :: startRequest:params -> ... wait, wait, wait ... -> HttpClass :: didReceiveResponse -> Class_A :: method_V:result and the last one: Class_B :: method_M -> HttpClass :: startRequest:params -> ... wait, wait, wait ... -> HttpClass :: didReceiveResponse -> Class_B :: method_N:result Please note, that the methods in Class_A and Class_B have different names and functionality, they just make us of the same HttpClass. My solution now would be to pass a C function pointer to startRequest, store it in the HttpClass and when didReceiveResponse gets called I invoke the function pointer and pass the result (which will always be a JSON Dictionary). Now I'm wondering if there can be any problems using plain C or if there are better solutions doing it in a more Objective-C way. Any ideas?

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• How can I set a Java applet transparency to show contents behind it?

  - by yuri

  I've got a web page with an applet inside. This applet is a drop target on a drag and drop action from the OS, I simply take an image from a folder, drag it on the applet and something happens. I give this webpage to a graphic designer and he ask to if he can put an image behind the java applet so he can simulate to change the background using CSS (it is a skinned app and graphic design can change during execution). Practically i supposed to do: <div> <applet width="50" height="50" /> </div> with this CSS: div { width:50px; height:50px; background-image: url(image.jpg) center center no-repeat; } But it doesn't work (background is opaque). It is possible to set transparency to the applet without loosing drag and drop capabilities ? I'm searching something similar to flash wmode parameter. Better solutions implies only changes on the CSS/HTML without recompiling java class so the designing team can change the page structure without changing the Java.

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• Which languages and techniques can I use to improve my coding practices?

  - by Danjah

  I've been offered the opportunity upskill through study, while at work which is great. My background I am mostly self-taught, but have worked with many excellent people over the years - both self-taught and fully educated, and on many decent projects. I have mild experience in Actionscript, I'm getting better every day with my Javascript, and my CSS is angled at best practice, but needs a bit of modernising. I'm a traditional interface developer, I'm not stupid and I like a challenge. My goal I need to start seeing ways of applying better logic, optimising code, refactoring, different styles of development (agile, others?), and.. well I need to try and start thinking like.. a more solid programmer. Its hard to describe, I have good solutions and I'm efficient - but I KNOW that there's a bunch I am missing. I am already employed with a solid career, but I feel the need to fill gaps. My question/s Are there a set of guiding principles you can recommend I focus on to improve the points above? Are there particular programming languages which I might focus on to get a broader overview? Do you think I should avoid particular styles of development, or even languages, while solidifying what might end up being part 'the basics' but hopefully 'advanced programming'? -- Sorry if this appears off topic or something but I figure you're probably some of the best people to ask.

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• Android XmlSerializer limitation?

  - by Rexb

  Hi all, My task is just to get an xml string using XmlSerializer. Problem is that it seems like the serializer stops adding any new element and/or attribute to the xml document when it reaches certain length (perhaps 10,000 char?). My questions: have you experience this kind of problem? What could be possible solutions? Here is my sample test code: public void doSerialize() throws XmlPullParserException, IllegalArgumentException, IllegalStateException, IOException { StringWriter writer = new StringWriter(); XmlSerializer serializer = XmlPullParserFactory.newInstance().newSerializer(); serializer.setOutput(writer); serializer.startDocument(null, null); serializer.startTag(null, "START"); for (int i = 0; i < 20; i++) { serializer.attribute(null, "ATTR" + i, "VAL " + i); } serializer.startTag(null, "DATA"); for (int i = 0; i < 500; i++) { serializer.attribute(null, "attr" + i, "value " + i); } serializer.endTag(null, "DATA"); serializer.endTag(null, "START"); serializer.endDocument(); String xml = writer.toString(); // value: until 493rd attribute int n = xml.length(); // value: 10125 } Any help will be greatly appreciated.

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• Rails: creating a custom data type, to use with generator classes and a bunch of questions related t

  - by Shyam

  Hi, After being productive with Rails for some weeks, I learned some tricks and got some experience with the framework. About 10 days ago, I figured out it is possible to build a custom data type for migrations by adding some code in the Table definition. Also, after learning a bit about floating points (and how evil they are) vs integers, the money gem and other possible solutions, I decided I didn't WANT to use the money gem, but instead try to learn more about programming and finding a solution myself. Some suggestions said that I should be using integers, one for the whole numbers and one for the cents. When playing in script/console, I discovered how easy it is to work with calculations and arrays. But, I am talking to much (and the reason I am, is to give some sufficient background). Right now, while playing with the scaffold generator (yes, I use it, because I like they way I can quickly set up a prototype while I am still researching my objectives), I like to use a DRY method. In my opinion, I should build a custom "object", that can hold two variables (Fixnum), one for the whole, one for the cents. In my big dream, I would be able to do the following: script/generate scaffold Cake name:string description:text cost:mycustom Where mycustom should create two integer columns (one for wholes, one for cents). Right now I could do this by doing: script/generate scaffold Cake name:string description:text cost_w:integer cost_c:integer I had also had an idea that would be creating a "cost model", which would hold two columns of integers and create a cost_id column to my scaffold. But wouldn't that be an extra table that would cause some kind of performance penalty? And wouldn't that be defy the purpose of the Cake model in the first place, because the costs are an attribute of individual Cake entries? The reason why I would want to have such a functionality because I am thinking of having multiple "costs" inside my rails application. Thank you for your feedback, comments and answers! I hope my message got through as understandable, my apologies for incorrect grammar or weird sentences as English is not my native language.

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• How to change the date/time in Python for all modules?

  - by Felix Schwarz

  When I write with business logic, my code often depends on the current time. For example the algorithm which looks at each unfinished order and checks if an invoice should be sent (which depends on the no of days since the job was ended). In these cases creating an invoice is not triggered by an explicit user action but by a background job. Now this creates a problem for me when it comes to testing: I can test invoice creation itself easily However it is hard to create an order in a test and check that the background job identifies the correct orders at the correct time. So far I found two solutions: In the test setup, calculate the job dates relative to the current date. Downside: The code becomes quite complicated as there are no explicit dates written anymore. Sometimes the business logic is pretty complex for edge cases so it becomes hard to debug due to all these relative dates. I have my own date/time accessor functions which I use throughout my code. In the test I just set a current date and all modules get this date. So I can simulate an order creation in February and check that the invoice is created in April easily. Downside: 3rd party modules do not use this mechanism so it's really hard to integrate+test these. The second approach was way more successful to me after all. Therefore I'm looking for a way to set the time Python's datetime+time modules return. Setting the date is usually enough, I don't need to set the current hour or second (even though this would be nice). Is there such a utility? Is there an (internal) Python API that I can use?

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• How to obtain the panel within a treeview (WPF)

  - by sperling

  How can one obtain the panel that is used within a TreeView? I've read that by default TreeView uses a VirtualizingStackPanel for this. When I look at a TreeView template, all I see is <ItemsPresenter />, which seems to hide the details of what panel is used. Possible solutions: 1) On the treeview instance ("tv"), from code, do this: tv.ItemsPanel. The problem is, this does not return a panel, but an ItemsPanelTemplate ("gets or sets the template that defines the panel that controls the layout of the items"). 2) Make a TreeView template that explicitly replaces <ItemsPresenter /> with your own ItemsControl.ItemsPanel. I am providing a special template anyways, so this is fine in my scenario. Then give a part name to the panel that you place within that template, and from code you can obtain that part (i.e. the panel). The problem with this? see below. (I am using a control named VirtualTreeView which is derived from TreeView, as is seen below): , use following: -- [sorry folks about poor formatting here, this is my first post, I tried 4 spaces for code... doesn't seem to work?] [I stripped out all clutter here for visibility...] The problem with this is: this immediately overrides any TreeView layout mechanism. Actually, you just get a blank screen, even when you have TreeViewItems filling the tree. Well, the reason I want to get a hold of the panel is to take some part in the MeaureOverride, but without going into all of that, I certainly do not want to rewrite the book of how to layout a treeview. I.e., doing this the step #2 way seems to invalidate the point of even using a TreeView in the first place. Sorry if there is some confusion here, thanks for any help you can offer.

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• How to make HTML layout whitespace-agnostic?

  - by ssg

  If you have consecutive inline-blocks white-space becomes significant. It adds some level of space between elements. What's the "correct" way of avoiding whitespace effect to HTML layout if you want those blocks to look stuck to each other? Example: <span>a</span> <span>b</span> This renders differently than: <span>a</span><span>b</span> because of the space inbetween. I want whitespace-effect to go away without compromising HTML source code layout. I want my HTML templates to stay clean and well-indented. I think these options are ugly: 1) Tweaking text-indent, margin, padding etc. (Because it would be dependent on font-size, default white-space width etc) 2) Putting everything on a single line, next to each other. 3) Zero font-size. That would require overriding font-size in blocks, which would otherwise be inherited. 4) Possible document-wide solutions. I want the solution to stay local for a certain block of HTML. Any ideas, any obvious points which I'm missing?

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• Problem with displaying image from DB using asp.net MVC 2

  - by Renato

  Hello! I'm having trouble with displaying image from db. I think that method for saving image is working, because I see in DB that varbinary fields have some value, and that image type is correct. Also the size of image. But when I want to display image for product i don't get anything. Just blank space.. here is my code... public byte[] GetImage(int productID) { Product product = products.GetByID(productID); byte[] imageData = product.ImageData.ToArray(); return imageData; } That code is in my controller. Second is code from view : <% if (product.ImageData != null) { %> <img src='/product/getimage/<%= Html.Encode(product.ID) %>' alt=""/> <% } %> I tried some solutions found here on stack overflow, and everyone do it like this, but it's working for them. I dont have any idea why images aren't displayed. When i look at source code of page at debugging i have : <img src='/product/getimage/18' alt=""/> I'm using .net 4.0, MVC 2, VS 2010... Thanks in advance

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• Archiver Securing SQLite Data without using Encryption on iPhone

  - by Redrocks

  I'm developing an iphone app that uses Core Data with a SQLite data store and lots of images in the resource bundle. I want a "simple" way to obfuscate the file structure of the SQLite database and the image files to prevent the casual hacker/unscrupulous developer from gaining access to them. When the app is deployed, the database file and image files would be obfuscated. Upon launching the app it would read in and un-obfuscate the database file, write the un-obfuscated version to the users "tmp" directory for use by core data, and read/un-obfuscate image files as needed. I'd like to apply a simple algorithm to the files that would somehow scramble/manipulate the file data so that the sqlite database data isn't discernible when the db is opened in a text editor and so that neither is recognized by other applications (SQLite Manager, Photoshop, etc.) It seems, from the information I've read, that I could use NSFileManager, NSKeyedArchiver, and NSData to accomplish this but I'm not sure how to proceed. Been developing software for many years but I'm new to everything CocoaTouch, Mac and iPhone. Also never had to secure/encrypt my data so this is new. Any thoughts, suggestions, or links to solutions are appreciated.

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• Storyboard Bug - iOS 5.1 - Xcode 4.3.3

  - by user1505431

  In my iOS project (using xcode only), I continue to run into a problem where layout presented to me in the storyboard editor becomes automatically modified after some change (which I have not been able to specifically determine). The problem is as follows: The TabBarController has for whatever reason started displaying in landscape orientation. Some of the NavigationControllers have also done the same thing. I can no longer see or edit the navigation bar on my nested views. I can no longer see of edit the tab bar on the views of the resp. tab bar items. Everything works properly when I run the app in my simulator. If I had set it up prior to this change in default display settings, it still works just fine. Here is a screen shot of the problem: My storyboard has consistently presented me with this bug throughout the course of my project. I have fixed it once by resetting via git and another time by rebuilding the entire storyboard. Both solutions worked for an extended period of time, but I would rather have a permanent solution. Any input would be helpful.

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• FOSS ASP.Net Session Replication Solution?

  - by jsight

  I've been searching (with little success) for a free/opensource session clustering and replication solution for asp.net. I've run across the usual suspects (indexus sharedcache, memcached), however, each has some limitations. Indexus - Very immature, stubbed session interface implementation. Its otherwise a great caching solution, though. Memcached - Little replication/failover support without going to a db backend. Several SF.Net projects - All aborted in the early stages... nothing that appears to have any traction, and one which seems to have gone all commercial. Microsoft Velocity - Not OSS, but seems nice. Unfortunately, I didn't see where CTP1 supported failover, and there is no clear roadmap for this one. I fear that this one could fall off into the ether like many other MS dev projects. I am fairly used to the Java world where it is kind of taken for granted that many solutions to problems such as this will be available from the FOSS world. Are there any suitable alternatives available on the .Net world?

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• Cocos2d - smooth sprite movement in tile map RPG

  - by Lendo92

  I've been working on a 2-D Gameboy style RPG for a while now, and the game logic is mostly all done so I'm starting to try to make things look good. One thing I've noticed is that the walking movement / screen movement is a little bit choppy. Technically, it should work fine, but either it seems to be having some quirks, either due to taking up a lot of processing power or just timing inconsistencies between moving the screen and moving the sprite. To move the sprite, once I know where I want to move it, I call: tempPos.y += 3*theHKMap.tileSize.width/5; id actionMove = [CCMoveTo actionWithDuration:0.1 position:tempPos]; id actionMoveDone = [CCCallFuncN actionWithTarget:self selector:@selector(orientOneMove)]; [guy runAction:[CCSequence actions:actionMove, actionMoveDone, nil]]; [self setCenterOfScreen:position]; Then, in orientOneMove, I call: [self.guy setTexture:[[CCTextureCache sharedTextureCache] addImage:@"guysprite07.png"]]; //the walking picture-I change texture back at the end of the movement id actionMove = [CCMoveTo actionWithDuration:0.15 position:self.tempLocation2]; id actionMoveDone = [CCCallFuncN actionWithTarget:self selector:@selector(toggleTouchEnabled)]; [guy runAction:[CCSequence actions:actionMove, actionMoveDone, nil]]; The code for the concurrently running setCenterOfScreen:position method is: id actionMove = [CCMoveTo actionWithDuration:0.25 position:difference]; [self runAction: [CCSequence actions:actionMove, nil, nil]]; So the setCenterOfScreen moves the camera in one clean move while the guy moving is chopped into two actions to animate it (which I believe might be inefficient.) It's hard to tell what is making the movement not perfectly clean from looking at it, but essentially the guy isn't always perfectly in the center of the screen -- during movement, he's often times a pixel or two off for an instant. Any ideas/ solutions?

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• Circular Reference exception with JSON Serialisation with MVC3 and EF4 CTP5w

  - by nakchak

  Hi I'm having problems with a circular reference when i try and serialise an object returned via EF4 CTP5. Im using the code first approach and simple poco's for my model. I have added [ScriptIgnore] attributes to any properties that provide a back references to an object and annoyingly every seems to work fine if i manually instantiate the poco's, i.e. they serialise to JSON fine, and the scriptignore attribute is acknowledged. However when i try and serialise an object returned from the DAL i get the circular reference exception "A circular reference was detected while serializing an object of type 'System.Data.Entity.DynamicProxies.xxxx'" I have tried several ways of retreiving the data but they all get stuck with this error: public JsonResult GetTimeSlot(int id) { TimeSlotDao tsDao = new TimeSlotDao(); TimeSlot ts = tsDao.GetById(id); return Json(ts); } The method below works slightly better as rather than the timeslot dynamic proxied object causing the circular refference its the appointment object. public JsonResult GetTimeSlot(int id) { TimeSlotDao tsDao = new TimeSlotDao(); var ts = from t in tsDao.GetQueryable() where t.Id == id select new {t.Id, t.StartTime, t.Available, t.Appointment}; return Json(ts); } Any ideas or solutions to this problem? Update I would prefer to use the out of the box serialiser if possible although Json.Net via nuget is ok as an alternative i would hope its possible to use it as I intended as well...

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• Non standard interaction among two tables to avoid very large merge

  - by riko

  Suppose I have two tables A and B. Table A has a multi-level index (a, b) and one column (ts). b determines univocally ts. A = pd.DataFrame( [('a', 'x', 4), ('a', 'y', 6), ('a', 'z', 5), ('b', 'x', 4), ('b', 'z', 5), ('c', 'y', 6)], columns=['a', 'b', 'ts']).set_index(['a', 'b']) AA = A.reset_index() Table B is another one-column (ts) table with non-unique index (a). The ts's are sorted "inside" each group, i.e., B.ix[x] is sorted for each x. Moreover, there is always a value in B.ix[x] that is greater than or equal to the values in A. B = pd.DataFrame( dict(a=list('aaaaabbcccccc'), ts=[1, 2, 4, 5, 7, 7, 8, 1, 2, 4, 5, 8, 9])).set_index('a') The semantics in this is that B contains observations of occurrences of an event of type indicated by the index. I would like to find from B the timestamp of the first occurrence of each event type after the timestamp specified in A for each value of b. In other words, I would like to get a table with the same shape of A, that instead of ts contains the "minimum value occurring after ts" as specified by table B. So, my goal would be: C: ('a', 'x') 4 ('a', 'y') 7 ('a', 'z') 5 ('b', 'x') 7 ('b', 'z') 7 ('c', 'y') 8 I have some working code, but is terribly slow. C = AA.apply(lambda row: ( row[0], row[1], B.ix[row[0]].irow(np.searchsorted(B.ts[row[0]], row[2]))), axis=1).set_index(['a', 'b']) Profiling shows the culprit is obviously B.ix[row[0]].irow(np.searchsorted(B.ts[row[0]], row[2]))). However, standard solutions using merge/join would take too much RAM in the long run. Consider that now I have 1000 a's, assume constant the average number of b's per a (probably 100-200), and consider that the number of observations per a is probably in the order of 300. In production I will have 1000 more a's. 1,000,000 x 200 x 300 = 60,000,000,000 rows may be a bit too much to keep in RAM, especially considering that the data I need is perfectly described by a C like the one I discussed above. How would I improve the performance?

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• Entity Framework autoincrement key

  - by Tommy Ong

  I'm facing an issue of duplicated incremental field on a concurrency scenario. I'm using EF as the ORM tool, attempting to insert an entity with a field that acts as a incremental INT field. Basically this field is called "SequenceNumber", where each new record before insert, will read the database using MAX to get the last SequenceNumber, append +1 to it, and saves the changes. Between the getting of last SequenceNumber and Saving, that's where the concurrency is happening. I'm not using ID for SequenceNumber as it is not a unique constraint, and may reset on certain conditions such as monthly, yearly, etc. InvoiceNumber | SequenceNumber | DateCreated INV00001_08_14 | 1 | 25/08/2014 INV00001_08_14 | 1 | 25/08/2014 <= (concurrency is creating two SeqNo 1) INV00002_08_14 | 2 | 25/08/2014 INV00003_08_14 | 3 | 26/08/2014 INV00004_08_14 | 4 | 27/08/2014 INV00005_08_14 | 5 | 29/08/2014 INV00001_09_14 | 1 | 01/09/2014 <= (sequence number reset) Invoice number is formatted based on the SequenceNumber. After some research I've ended up with these possible solutions, but wanna know the best practice 1) Optimistic Concurrency, locking the table from any reads until the current transaction is completed (not fancy of this idea as I guess performance will be of a great impact?) 2) Create a Stored Procedure solely for this purpose, does select and insert on a single statement as such concurrency is at minimum (would prefer a EF based approach if possible)

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• Display two array's in the same table

  - by Naeem Ahmed

  $row = $query->fetchAll(PDO::FETCH_ASSOC); $num_rows = count($row); for ($i = 0; $i < $num_rows; $i++) { $title = htmlspecialchars($row[$i]['title']); $author =htmlspecialchars($row[$i]['author']); $school =htmlspecialchars($row[$i]['school']); $solution = $row[$i]['solution']; $notes = $row[$i]['notes']; $ad = array($title, $price, $author, $school, $contact, $content, $date); $inlcude = array($solutions, $notes); $field = 0; echo "<table border='1'>"; // foreach($inlcude as $in) This failled miserably foreach ($ad as $post) { if ($field < 3) //The first three values are placed in the first row { echo "<td>$post</td>"; } if ($field >= 3) { echo "<tr><td>$post</td><td>$in</td></tr>"; } $field++; } echo '</table>'; } I have two arrays and I would like to display them in different columns in my table. $ad displays perfectly fine but I'm having trouble displaying the contents in $inlcude in the second column. I've tried putting another foreach loop to iterate through contents of the second array but that really screws up my table by placing random values in different places on the table. Besides the foreach loop, I don't know of any other way to iterate through the array. Any suggestions would be appreciated.Thanks!

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• mysql: storing arbitrary data

  - by Hailwood

  Background: I was asking a question on stack overflow regarding creating tables on the fly where this conversation ensued: This smells like a terrible idea! In fact, it smells just like this one. What in the world do you want to use this for? – deceze @deceze: very true, However, How else would you store the contents of these CSV files. They must be stored in mysql for indexing. The only solid fact about them is that they all have a mobile column with a standard format. The CSV can have an arbitrary amount of columns with an arbitrary amount of rows. They can (with no exaggeration) range from a single row, 35 column csv to an 80k row single column CSV. I am open to other ideas. – Hailwood There are many solutions for this, from attribute-value schemas to JSON storage and NoSQL storage. Open a new question about it. Whatever you do though, don't dynamically create tables! – deceze Question: So my question is, What would you say is the best way to store this data? Are you in agreement with deceze about not creating dynamic tables?

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• How do you make life easier for yourself when developing a really large database

  - by Hannes de Jager

  I am busy developing 2 web based systems with MySql databases and the amount of tables/views/stored routines is really becoming a lot and it is more and more challenging to handle the complexity. Now in programming languages we have namespacing e.g. Java packages, C++ namespaces to partition the software, grouping it together to make things more understandable. Databases on the other hand have more of a flat structure (MySql at least) e.g. tables and stored procedures are on the same level. So one have to be more creative, creating naming conventions, perhaps use more than one database or using tools to visualize things. What methods do you use to ease the pain? To be effective while developing your databases? To not get lost in a sea of tables and fields and stored procs? Feel free to mention tools you use also, but try to restrict it to open source and preferably Linux solutions if thats OK. b.t.w How many tables would a database have to be considered large in terms of design?

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• handling pointer to member functions within hierachy in C++

  - by anatoli

  Hi, I'm trying to code the following situation: I have a base class providing a framework for handling events. I'm trying to use an array of pointer-to-member-functions for that. It goes as following: class EH { // EventHandler virtual void something(); // just to make sure we get RTTI public: typedef void (EH::*func_t)(); protected: func_t funcs_d[10]; protected: void register_handler(int event_num, func_t f) { funcs_d[event_num] = f; } public: void handle_event(int event_num) { (this->*(funcs_d[event_num]))(); } }; Then the users are supposed to derive other classes from this one and provide handlers: class DEH : public EH { public: typedef void (DEH::*func_t)(); void handle_event_5(); DEH() { func_t f5 = &DEH::handle_event_5; register_handler(5, f5); // doesn't compile ........ } }; This code wouldn't compile, since DEH::func_t cannot be converted to EH::func_t. It makes perfect sense to me. In my case the conversion is safe since the object under this is really DEH. So I'd like to have something like that: void EH::DEH_handle_event_5_wrapper() { DEH *p = dynamic_cast<DEH *>(this); assert(p != NULL); p->handle_event_5(); } and then instead of func_t f5 = &DEH::handle_event_5; register_handler(5, f5); // doesn't compile in DEH::DEH() put register_handler(5, &EH::DEH_handle_event_5_wrapper); So, finally the question (took me long enough...): Is there a way to create those wrappers (like EH::DEH_handle_event_5_wrapper) automatically? Or to do something similar? What other solutions to this situation are out there? Thanks.

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