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• xpath help substring expression

  - by NA

  Hi i have a document from which i am trying to extract a date. But the problem is within the node along with the date their is some text too. Something like <div class="postHeader"> Posted on July 20, 2009 9:22 PM PDT </div> From this tag i just want the date item not the Posted on text. something like ./xhtml:div[@class = 'postHeader'] is getting everything. and to be precise, the document i have is basically a nodelist of this elements for eg i will get 10 nodes of these elements with different date values but to be worse the problem is sometime inside these tags some random other tags also pops us like anchors etc. Can i write a universal expath which will just get the date out of the div tag?

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• g_tree_insert overwrites all data

  - by pechenie

  I wonder how I should use the GTree (from GLib) to store data? Every new value I insert into GTree with g_tree_insert routine is overwrite the previous one! GTree *tree; //init tree = g_tree_new( g_str_equal ); //"g_str_equal" is a GLib default compare func //... for( i = 0; i < 100; ++i ) g_tree_insert( tree, random_key(), random_value() ); //insert some random vals // printf( "%d", g_tree_nnodes( tree ) ); //should be 100? NO! Prints "1"!!! What am I doing wrong? Thank you.

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• PHP While Loops from Arrays

  - by Michael

  I have a table that contains members names and a field with multiple ID numbers. I want to create a query that returns results where any values in the ID fields overlap with any values in the array. For example: lastname: Smith firstname: John id: 101, 103 I have Array #1 with the values 101, 102, 103 I want the query to output all members who have the values 101 or 102 or 103 listed in their id field with multiple ids listed. Array ( [0] => 101 [1] => 102 [2] => 103 ) $sql="SELECT firstname, lastname, id FROM members WHERE id LIKE '%".$array_num_1."%'"; $result=mysql_query($sql); while ($rows=mysql_fetch_array($result)) { echo $rows['lastname'].', '.$rows['firstname'].'-'.$rows['id']; }

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• Translate imperative control flow with break-s/continue-s to haskell

  - by dorserg

  Consider the following imperative code which finds the largest palindrome among products of 3-digit numbers (yes, it's the one of the first tasks from "Project of [outstanding mathematician of 18th century]" site): curmax = 0 for i in range(999,100): for j in range(999,100): if ((i*j) < curmax): break if (pal(i*j)): curmax = i*j break print curmax As I'm learning Haskell currently, my question is, how do you translate this (and basically any imperative construct that contains something more complex than just plain iteration, e.g. breaks, continues, temporary variables and all this) to Haskell? My version is maxpal i curmax | i < 100 = curmax | otherwise = maxpal (i-1) (innerloop 999) where innerloop j | (j < 100) || (p < curmax) = curmax | pal p = p | otherwise = innerloop (j-1) where p = i*j main = print $ maxpal 999 0 but this looks like we're still in imperative uglytown. So what could you advise, what are the approaches of dealing with such cases FP-style?

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• problem with hierarchical clustering in Python

  - by user248237

  I am doing a hierarchical clustering a 2 dimensional matrix by correlation distance metric (i.e. 1 - Pearson correlation). My code is the following (the data is in a variable called "data"): from hcluster import * Y = pdist(data, 'correlation') cluster_type = 'average' Z = linkage(Y, cluster_type) dendrogram(Z) The error I get is: ValueError: Linkage 'Z' contains negative distances. What causes this error? The matrix "data" that I use is simply: [[ 156.651968 2345.168618] [ 158.089968 2032.840106] [ 207.996413 2786.779081] [ 151.885804 2286.70533 ] [ 154.33665 1967.74431 ] [ 150.060182 1931.991169] [ 133.800787 1978.539644] [ 112.743217 1478.903191] [ 125.388905 1422.3247 ]] I don't see how pdist could ever produce negative numbers when taking 1 - pearson correlation. Any ideas on this? thank you.

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• What to Learn: Rails 1.2.4 -> Rails 3

  - by Saterus

  I've recently convinced my management that our outdated version of Rails is slowing us down enough to warrant an upgrade. The approach we're taking is to start a fresh project with current technology rather than a painful upgrade. Our requirements for the project have changed and this will be much easier. The biggest problem is actually that my knowledge of Rails is out of date. I've dealt only with Rails 1.2.4 while the rest of the world has moved on long ago. What topics have I missed by being buried in my work instead of keeping up with the current Rails fashion? I'm hesitant to dig through blogs at random because I'm not sure how much has changed between the intervening versions of Rails. It's no use to learn Rails 2.1-2.3 specific stuff that is no longer useful for Rails 3.

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• How secure are GUIDs in terms of predictability?

  - by ssg

  We're using .NET's Guid.NewGuid() to generate activation codes and API keys currently. I wonder if that poses a security problem since their algorithm is open. .NET Guid uses Win32 CoCreateGuid and I don't know it's internals (possibly MAC address + timestamp?). Can someone derive a second GUID out of the first one, or can he hit it with some smart guesses or is the randomness good enough so search space becomes too big? Generating random keys have the problem of collision, they need a double check before adding to a database. That's why we stuck with GUIDs but I'm unsure about their security for these purposes. Here are the 4 consecutive UUIDGEN outputs: c44dc549-5d92-4330-b451-b29a87848993 d56d4c8d-bfba-4b95-8332-e86d7f204c1c 63cdf958-9d5a-4b63-ae65-74e4237888ea 6fd09369-0fbd-456d-9c06-27fef4c8eca5 Here are 4 of them by Guid.NewGuid(): 0652b193-64c6-4c5e-ad06-9990e1ee3791 374b6313-34a0-4c28-b336-bb2ecd879d0f 3c5a345f-3865-4420-a62c-1cdfd2defed9 5b09d7dc-8546-4ccf-9c85-de0bf4f43bf0

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• TcpListener Socket still active after program exits.

  - by lnical

  I'm trying to stop a TCP Listener as my program is exiting. I do not care about any data that is currently active on the socket or any of the active client sockets. The socket clean up code is essentially: try { myServer.Server.Shutdown(SocketShutdown.Both) } catch (Exception ex) { LogException(ex) } myServer.Server.Close(0) myServer.Stop() myServer is a TCPListener On some occasions, Shutdown will thrown an exception System.Net.Sockets.SocketException: A request to send or receive data was disallowed because the socket is not connected and (when sending on a datagram socket using a sendto call) no address was supplied at System.Net.Sockets.Socket.Shutdown(SocketShutdown how) When this happens, the socket is never released. Even after the application exits netstat shows the socket is still in the listening state. I have not been able to create definitive reproduction scenerio, it happens at seemingly random times. Client Sockets are cleaned up independently. Do you have any suggestions to help me make this socket die?

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• How to format a string as a telephone number in C#

  - by Brian G

  I have a string "1112224444' it is a telephone number. I want to format as 111-222-4444 before I store it in a file. It is on a datarecord and I would prefer to be able to do this without assigning a new variable. I was thinking: String.Format("{0:###-###-####}", i["MyPhone"].ToString() ); but that does not seem to do the trick. ** UPDATE ** Ok. I went with this solution Convert.ToInt64(i["Customer Phone"]).ToString("###-###-#### ####") Now its gets messed up when the extension is less than 4 digits. It will fill in the numbers from the right. so 1112224444 333 becomes 11-221-244 3334 Any ideas?

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• Splitting a double vector into equal parts

  - by Cosmin

  Greetings, Any input on a way to divide a std::vector into two equal parts ? I need to find the smallest possible difference between |part1 - part2|. This is how I'm doing it now, but from what you can probably tell it will yield a non-optimal split in some cases. auto mid = std::find_if(prim, ultim, [&](double temp) -> bool { if(tempsum >= sum) return true; tempsum += temp; sum -= temp; return false; }); The vector is sorted, highest to lowest, values can indeed appear twice. I'm not expecting part1 and part2 to have the same numbers of elements, but sum(part1) should be as close as possible to sum(part2) For example if we would have { 2.4, 0.12, 1.26, 0.51, 0.70 }, the best split would be { 2.4, 0.12 } and { 1.26, 0.51, 0.70 }. If it helps, I'm trying to achieve the splitting algorithm for the Shannon Fano encoding. Any input is appreciated, thanks!

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• Is there any way to provide custom factory for .Net Framework creation Entities from EF4 ?

  - by ILICH

  There are a lot of posts about how cool POCO objects are and how Entity Framework 4 supports them. I decided to try it out with domain driven development oriented architecture and finished with domain entities that has dependencies from services. So far so good. Imagine my Products are POCO objects. When i query for objects like this: NorthwindContext db = new NorthwindContext(); var products = db.Products.ToList(); EF creates instances of products for me. Now I want to inject dependencies in my POCO objects (products) The only way I see is make some method within NorthwindContext that makes something like pseudo-code below: public List<Product> GetProducts(){ var products = database.Products.ToList(); container.BuildUp(products); //inject dependencies return products; } But what if i want to make my repository to be more flexible like this: public ObjectSet<Product> GetProducts() { ... } So, I really need a factory to make it more lazy and linq friendly. Please help !

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• Rails: using find method to access joined tables for polymorphic relationships

  - by DJTripleThreat

  Ok, I have a generic TimeSlot model that deals with a start_at and an end_at for time spans. A couple models derive from this but I'm referring to one in this question: AppointmentBlock which is a collection of Appointments. I want to validate an AppointmentBlock such that no other AppointmentBlocks have been scheduled for a particular Employee in the same time frame. Since AppointmentBlock has a polymorphic association with TimeSlot, you have to access the AppointmentBlock's start_at and end_at through the TimeSlot like so: appt_block.time_slot.start_at This means that I need to have some kind of join in my :conditions for my find() method call. Here is my code so far: #inside my appointment_block.rb model validate :employee_not_double_booked def employee_not_double_booked unless self.employee_id # this find's condition is incorrect because I need to join time_slots to get access # to start_at and end_at. How can I do this? blocks = AppointmentBlock.find(:first, :conditions => ['employee_id = ? and (start_at between ? and ? or end_at between ? and ?)', self.employee_id, self.time_slot.start_at, self.time_slot.end_at, self.time_slot.start_at, self.time_slot.end_at]) # pseudo code: # collect a list of appointment blocks that end after this # apointment block starts or start before this appointment # block ends that are also associated with this appointment # blocks assigned employee # if the count is great then 0 the employee has been double # booked. # if a block was found that means this employee is getting # double booked so raise an error errors.add "AppointmentBlock", "has already been scheduled during this time" if blocks end end Since AppointmentBlock doesn't have a start_at or an end_at how can I join with the time_slots table to get those conditions to work?

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• Script Speed vs Memory Usage

  - by Doug Neiner

  I am working on an image generation script in PHP and have gotten it working two ways. One way is slow but uses a limited amount of memory, the second is much faster, but uses 6x the memory . There is no leakage in either script (as far as I can tell). In a limited benchmark, here is how they performed: -------------------------------------------- METHOD | TOTAL TIME | PEAK MEMORY | IMAGES -------------------------------------------- One | 65.626 | 540,036 | 200 Two | 20.207 | 3,269,600 | 200 -------------------------------------------- And here is the average of the previous numbers (if you don't want to do your own math): -------------------------------------------- METHOD | TOTAL TIME | PEAK MEMORY | IMAGES -------------------------------------------- One | 0.328 | 540,036 | 1 Two | 0.101 | 3,269,600 | 1 -------------------------------------------- Which method should I use and why? I anticipate this being used by a high volume of users, with each user making 10-20 requests to this script during a normal visit. I am leaning toward the faster method because though it uses more memory, it is for a 1/3 of the time and would reduce the number of concurrent requests.

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• imagecopyresampled to resize and crop an image - not returning the expected result

  - by David

  imagecopyresized ( resource $dst_image , resource $src_image , int $dst_x , int $dst_y , int $src_x , int $src_y , int $dst_w , int $dst_h , int $src_w , int $src_h ) This is what I want to do: I have an image that's 600x1000px in size, and I want to create a thumb that's 100x100px after resizing that image to 300x500px, the x coordinate for the top left point of the thumb square should be at 100(src x) and 120(src y). According to what I understand from the manual, the command should be $dst_image = imagecreatetruecolor(100,100); $src_image = imagecreatefromjpeg('/home/sandbox/imagetoresize.jpg'); imagecopyresized ($dst_image, $src_image, 0, 0, 100, 120, **300 , 500 , 600 , 1000** ) It is cropping the image just fine, but it isn't resizing it correctly. I never got it to match what I see in my image editor (the GIMP). What am I doing wrong? I confirmed that all the numbers are correct, but it's always shifted up or down no matter what I do. Your help would really be appreciated!

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• Can this loop be sped up in pure Python?

  - by Noctis Skytower

  I was trying out an experiment with Python, trying to find out how many times it could add one to an integer in one minute's time. Assuming two computers are the same except for the speed of the CPUs, this should give an estimate of how fast some CPU operations may take for the computer in question. The code below is an example of a test designed to fulfill the requirements given above. This version is about 20% faster than the first attempt and 150% faster than the third attempt. Can anyone make any suggestions as to how to get the most additions in a minute's time span? Higher numbers are desireable. EDIT: This experiment is being written in Python 3.1 and is 15% faster than the fourth speed-up attempt. def start(seconds): import time, _thread def stop(seconds, signal): time.sleep(seconds) signal.pop() total, signal = 0, [None] _thread.start_new_thread(stop, (seconds, signal)) while signal: total += 1 return total if __name__ == '__main__': print('Testing the CPU speed ...') print('Relative speed:', start(60))

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• C# dealing with invalid user input

  - by Zka

  Have a simple console app where user is asked for several values to input. Input is read via console.readline(). Ex Name: Fred //string Lastname: Ashcloud //string Age: 28 //int I would like to make sure that int and double types are entered and if the user enters garbage, lets him repeat the procedure. Example, if the user enters "28 years old" where age expects int the app will crash. What is the best way to check for these inputs? Right now I can only think of: while (!Int32.TryParse(text, out number)) { Console.WriteLine("Error write only numbers"); text = Console.ReadLine(); } Is there any other way to do this? try catch statements if one wants to give a more detailed feedback to the user? How in that case?

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• Efficiently Serving Dynamic Content in Google App Engine

  - by awegawef

  My app on google app engine returns content items (just text) and comments on them. It works like this (pseudo-ish code): query: get keys of latest content #query to datastore for each item in content if item_dict in memcache: use item_dict else: build_item_dict(item) #by fetching from datastore store item_dict in memcache send all item_dicts to template Sorry if the code isn't understandable. I get all of the content dictionaries and send them to the template, which uses them to create the webpage. My problem is that if the memcache has expired, for each item I want to display, I have to (1) lookup item in memcache, (2) since no memcache exists I must fetch item from the datastore, and (3) store the item in memcache. These calls build up quickly. I don't set an expire time for the entries to the memcache, so this really only happens once in the morning, but the webpage takes long enough to load (~1 sec) that the browser reports it as not existing. Regularly, my webpages take about 50ms to load. This approach works decently for frequent visits, but it has its flaws as shown above. How can I remedy this? The entries are dynamic enough that I don't think it would be in my best interest to cache my initial request. Thanks in advance

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• Generating changelogs from commit-comments - bad idea?

  - by Adam Asham

  I work for a small company (<10 developers) where we use Svn and to some extent Git. We have no release system implemented. We don't tag our applications with a release numbers so as you can imagine, we don't keep track of changes between releases very well. With this in mind I've been thinking about generating changelogs from the commit-comments. It doesn't have to be an awful idea if you implement guidelines for how to write comments. Or am I fooling myself thinking that colleagues will follow these guidelines? Most of them don't bother adding comments today but I'm hoping that will change if they become aware of how to formulate themselves and that you don't have to comment on every single commit. Or would we it be more wise to gather information from our bug/project managing software and write the changelogs manually (which unfortunately is something nobody wants to do)?

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• jQuery/javascript events - prototype event handler

  - by Brian M. Hunt

  The following code doesn't work as I intuitively expect it to: function MyObject(input) { input.change(this._foo); this.X = undefined; } MyObject.prototype._foo = function() { alert("This code is never called"); // but if it did this.X = true; } var test_input = $("input#xyz"); // a random, existing input var m = MyObject(test_input); // attach handler (or try to) test_input.change(); // trigger event alert(m.X); // undefined I'd expect that _foo() would be called (and, if that ever happens, that the this variable in _foo() would be an instantiation of MyObject. Does anyone know why this doesn't work, and of any alternative pattern for passing an object to an event handler? Thank you for reading. Brian

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• What's wrong with my logic (Java syntax)

  - by soda

  I'm trying to make a simple program that picks a random number and takes input from the user. The program should tell the user if the guess was hot (-/+ 5 units) or cold, but I never reach the else condition. Here's the section of code: public static void giveHint (int guess) { int min = guess - 5; int max = guess + 5; if ((guess > min) && (guess < max)) { System.out.println("Hot.."); } else { System.out.println("Cold.."); } }

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• Suggestion for creating custom sound recognition software to toggle audio

  - by Parrot owner

  I need to develop a program that toggles a particular audio track on or off when it recognizes a parrot scream or screech. The software would need to recognize a particular range of sounds and allow some variations in the range (as a parrot likely won't replicate its sreeches EXACTLY each time). Example: Bird screeches, no audio. Bird stops screeching for five seconds, audio track praising the bird plays. Regular chattering needs to be ignored completely, as it is not to be discouraged. I've heard of java libraries that have speech recognition with dictionaries built in, but the software would need to be taught the particular sounds that my particular parrot makes - not words or any random bird sound. In addition as I mentioned above, it would need to allow for slight variation in the sound, as the screech will likely never be 100% identical to the recorded version. What would be the best way to go about this/what language should I look into?

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• string parsing help

  - by sprugman

  I've got a string like this: #################### Section One #################### Data A Data B #################### Section Two #################### Data C Data D etc. I want to parse it into something like: $arr( 'Section One' => array('Data A', 'Data B'), 'Section Two' => array('Data C', 'Data D') ) At first I tried this: $sections = preg_split("/(\r?\n)(\r?\n)#/", $file_content); The problem is, the file isn't perfectly clean: sometimes there are different numbers of blank lines between the sections, or blank spaces between data rows. The section head pattern itself seems to be relatively consistent: #################### Section Title #################### The number of #'s is probably consistent, but I don't want to count on it. The white space on the title line is pretty random. Once I have it split into sections, I think it'll be pretty straightforward, but any help writing a killer reg ex to get it there would be appreciated. (Or if there's a better approach than reg ex...)

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• When using a HiLo ID generation strategy, what types should be used to hold Ids?

  - by UpTheCreek

  I'm asking this from a c#/NHibnernate perspective, but it's generally applicable. The concern is that the HiLo strategy goes though id's pretty quickly, and for example a low record-count table (Such as Users) is sharing from the same set of id's as a high record-count table (Such as comments). So you can potentially get to high numbers quicker that with other strategies. So what do people recommend? Code side: int/uint/long/ulong? DBSide: int/bigint? My feeling is to go with longs and bigingts, but would like a sanity check :)

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• Python: Count lines and differentiate between them

  - by Mister X

  I'm using an application that gives a timed output based on how many times something is done in a minute, and I wish to manually take the output (copy paste) and have my program, and I wish to count how many times each minute it is done. An example output is this: 13:48 An event happened. 13:48 Another event happened. 13:49 A new event happened. 13:49 A random event happened. 13:49 An event happened. So, the program would need to understand that 2 things happened at 13:48, and 3 at 13:49. I'm not sure how the information would be stored, but I need to average them after, to determine an average of how often it happens. Sorry for being so complicated!

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• Efficient algorithm for Next button on a MySQL result set

  - by David Grayson

  I have a website that lets people view rows in a table (each row is a picture). There are more than 100,000 rows. You can view different subsets of the rows, and you can view them with different sort orders. While you are viewing one of the rows, you can click the "Next" or "Previous" buttons to go the next/previous row in the list. How would you implement the "Next" and "Previous" features of the website? More specifically, if you have an arbitrary query that returns a list of up to 100,000+ rows, and you know some information about the current row someone is viewing, how do you determine the NEXT row efficiently? Here is the pseudo-code of the solution I came up with when the website was young, and it worked well when there were only 1000 rows, but now that there are 100,000 rows I think it is eating up too much memory. int nextRowId(string query, int currentRowId) { array allRowIds = mysql_query(query); // Takes up a lot of memory! int currentIndex = (index of currentRowId in allRowIds); // Takes time! return allRowIds[currentIndex+1]; } While you are thinking about this problem, remember that the website can store more information about the current row than just its ID (for example, the position of the current row in the result set), and this information can be used as a hint to help determine the ID of the next row. Edit: Sorry for not mentioning this earlier, but this isn't just a static website: rows can often be added to the list, and rows can be re-ordered in the list. (Much rarer, rows can be removed from the list.) I think that I should worry about that kind of thing, but maybe you can convince me otherwise.

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