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  • Most useful Python modules from the standard library?

    - by EOL
    I am teaching a graduate level Python class at the University of Paris, and the students need to be introduced to the standard library. I want to discuss with them about some of the most important standard modules. What modules do you think are absolute musts? Even though responses probably vary depending on your field (web programming, science, etc.), I feel that some modules are commonly needed: math, sys, re, os, os.path, logging,… and maybe: collections, struct,… What modules would you suggest I present, in a 1 or 2 hour slot?

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  • Getting pixel averages of a vector sitting atop a bitmap...

    - by user346511
    I'm currently involved in a hardware project where I am mapping triangular shaped LED to traditional bitmap images. I'd like to overlay a triangle vector onto an image and get the average pixel data within the bounds of that vector. However, I'm unfamiliar with the math needed to calculate this. Does anyone have an algorithm or a link that could send me in the right direction? (I tagged this as Python, which is preferred, but I'd be happy with the general algorithm!) I've created a basic image of what I'm trying to capture here: http://imgur.com/Isjip.gif

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  • using pthread in c++

    - by ogzylz
    I am using pthread.h in a *.cc file. when I try to use pthread_exit(0); or pthread_join(mythrds[yy],NULL); it says : .cc:(.text+0x3e): undefined reference to `pthread_exit' when complied very similar code in a *.c file with gcc it work perfect. How Can I use pthread's in c++.. (I also added -lpthread) .. void *myThreads ( void *ptr ) { ... pthread_exit(0); } .. flags: g++ -lpthread -Wall -static -W -O9 -funroll-all-loops -finline -ffast-math

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  • Random number within a range based on a normal distribution

    - by ConfusedAgain
    I'm math challenged today :( I want to generate random numbers with a range (n to m, eg 100 to 150), but instead of purely random I want the results to be based on the normal distribution. By this I mean that in general I want the numbers "clustered" around 125. I've found this random number package that seems to have a lot of what I need: http://beta.codeproject.com/KB/recipes/Random.aspx It supports a variety of random generators (include mersiene twister) and can apply the generator to a distribution. But I'm confused... if I use a normal distribution generator the random numbers are from roughly -6 to +8 (apparently the true range is float.min to float.max). How do a scale that to my required range?

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  • Project generation problem using Spring Roo

    - by Harry
    Hi, I just downloaded SpringSource Tool Suite, and tried to generate a demo application using roo, but i'm getting error below Code: Created /home/dev/springsource/workspace/demo/pom.xml Undo create /home/dev/springsource/workspace/demo/pom.xml Invalid dependency scope: PROVIDED [Timer-0] NullPointerException at org.springframework.roo.classpath.itd.AbstractItdMetadataProvider.notify(AbstractItdMetadataProvider.java:84) What is the problem? is this Maven issue? Using: Ubuntu 8.10, SpringSource Tool Suite Version: 2.3.3.M1, Roo 1.1.0.M1, Apache Maven Thanks

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  • How to replace the deprecated csc ant task

    - by GrGr
    I have a mixed Java / C# project and use an ant script that contains a csc task to compile the dll. This works, but I get a warning [csc] This task is deprecated and will be removed in a future version [csc] of Ant. It is now part of the .NET Antlib: [csc] http://ant.apache.org/antlibs/dotnet/index.html How can I replace the csc task? I can surely create an exec task calling nant with a project.build file, but that feels completely wrong.

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  • Should I use implicit conversions to enforce preconditions?

    - by Malvolio
    It occurs to me that I could use use implicit conversions to both announce and enforce preconditions. Consider this: object NonNegativeDouble { implicit def int2nnd(d : Double) : NonNegativeDouble = new NonNegativeDouble(d) implicit def nnd2int(d : NonNegativeDouble) : Double = d.v def sqrt(n : NonNegativeDouble) : NonNegativeDouble = scala.math.sqrt(n) } class NonNegativeDouble(val v : Double ) { if (v < 0) { throw new IllegalArgumentException("negative value") } } object Test { def t1 = { val d : Double = NonNegativeDouble.sqrt(3.0); printf("%f\n", d); val n : Double = NonNegativeDouble.sqrt(-3.0); } } Ignore for the moment the actual vacuity of the example: my point is, the subclass NonNegativeDouble expresses the notion that a function only takes a subset of the entire range of the class's values. First is this: A good idea, a bad idea, or an obvious idea everybody else already knows about Second, this would be most useful with basic types, like Int and String. Those classes are final, of course, so is there a good way to not only use the restricted type in functions (that's what the second implicit is for) but also delegate to all methods on the underlying value (short of hand-implementing every delegation)?

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  • Beginner Java Question about Integer.parseInt() and casting

    - by happysoul
    so when casting like in the statement below :- int randomNumber=(int) (Math.random()*5) it causes the random no. generated to get converted into an int.. Also there's this method I just came across Integer.parseInt() which does the same ! i.e return an integer Why two different ways to make a value an int ? Also I made a search and it says parseInt() takes string as an argument.. So does this mean that parseInt() is ONLY to convert String into integer ? What about this casting then (int) ?? Can we use this to convert a string to an int too ? sorry if it sounds like a dumb question..I am just confused and trying to understand Help ?

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  • Request size limitation when using MultipartHttpServletRequest of Spring 3.0

    - by Spiderman
    I'd like to know what is the size limitation if I upload list of files in one client's form submition using HTTP multipart content type. On the server side I am using Spring's MultipartHttpServletRequest to handle the request. mM questions: Is there should be different file size limitation and total request size limitation or file size is the only limitation and the request is capable of uploading 100s of files as lonng as they are not too large. Doest the Spring request wrapper read the complete request and store it in the JAVA heap memory or it store temporaray files of it to be able to use big quota. Is the use of reading the httpservlet request in streaming would change the size limitation than using complete http request read at-once by the application server. What is the bottleneck of this process - Java heap size, the quota of the filesystem on which my web-server runs, the maximum allowed BLOB size that the DataBase in which I am gonna save the file alows? or Spring internal limitations? Related threads that still don't have exact answer to this: does-spring-framework-support-streaming-mode-in-mutlipart-requests is-there-a-way-to-get-raw-http-request-stream-from-java-servlet-handler how-to- drop-body-of-a-request-after-checking-headers-in-servlet apache-commons-fileupload-throws-malformedstreamexception

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  • Setting tabindex in dynamic table vertically then horizontally

    - by Wil
    I have a page that is currently generating dynamically created textboxes in a table format. The users are requesting that the tab order be changed from horizontal-vertical to vertical-horizontal. I know that you can use the tabindex attribute to control the tab ordering, but I can't for the life of me figure out the right way to get the sequential number properly for the textboxes. I guess this is more of a math question than anything else! FYI, the textboxes are made while looping two different collections. First collection looped to make the rows, for each row, second collection (which is a property of the first collection objects) is looped to create the columns. Any help would be greatly appreciated. Thanks!

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  • How can I rotate an image using Java/Swing and then set its origin to 0,0?

    - by JT
    I'm able to rotate an image that has been added to a JLabel. The only problem is that if the height and width are not equal, the rotated image will no longer appear at the JLabel's origin (0,0). Here's what I'm doing. I've also tried using AffineTransform and rotating the image itself, but with the same results. Graphics2D g2d = (Graphics2D)g; g2d.rotate(Math.toRadians(90), image.getWidth()/2, image.getHeight()/2); super.paintComponent(g2d); If I have an image whose width is greater than its height, rotating that image using this method and then painting it will result in the image being painted vertically above the point 0,0, and horizontally to the right of the point 0,0.

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  • Direct video card access

    - by icemanind
    Guys, I am trying to write a class in C# that can be used as a direct replacement for the C# Bitmap class. What I want to do instead though is perform all graphic functions done on the bitmap using the power of the video card. From what I understand, functions such as DrawLine or DrawArc or DrawText are primitive functions that use simple cpu math algorithms to perform the job. I, instead, want to use the graphics card cpu and memory to do these and other advanced functions, such as skinning a bitmap (applying a texture) and true transparancy. My problem is, in C#, how do I access direct video functions? Is there a library or something I need?

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  • Does this variable need to be declared volatile?

    - by titaniumdecoy
    Does the out variable in the MyThread class need to be declared volatile in this code or will the "volatility" of the stdout variable in the ThreadTest class carry over? import java.io.PrintStream; class MyThread implements Runnable { int id; PrintStream out; // should this be declared volatile? MyThread(int id, PrintStream out) { this.id = id; this.out = out; } public void run() { try { Thread.currentThread().sleep((int)(1000 * Math.random())); out.println("Thread " + id); } catch (InterruptedException e) { e.printStackTrace(); } } } public class ThreadTest { static volatile PrintStream stdout = System.out; public static void main(String[] args) { for (int i = 0; i < 10; i++) { new Thread(new MyThread(i, stdout)).start(); } } }

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  • Use my own authentication in tomcat

    - by mabuzer
    how can I force tomcat to use my own implementation of Authenticator, and not the existing one like [FORM, BASIC, DIGEST,, etc]. I know if I added my authentication class name in org.apache.catalina.startup.Authenticators.properties it would work,,, any help please... I need an alternative for this...

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  • How to extend a large website to iPhone app?

    - by xoail
    I am trying to create an iphone app for a large website (as big as amazon.com) and it involves using cookies and what not to get authenticated via the apache intercepter and access the web services exposed by the main website. For that I am looking for strategies to go about developing it. I am new to iphone dev and mostly looking for some architectural guidance. Does anyone know how does apps like ebay and amazon work seamlessly across the website and iphone?

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  • Integers in JavaScript

    - by muntoo
    I'm a beginner to Javascript so forgive me if I sound dumb because I learned some Javascript from W3Fools (which are really difficult tutorials - they don't explain anything I want to know, but everything I probably can guess from my experience with C++). I may be switching over to MDN, but if you can recommend any other tutorials, that be great. Anyways, so here's my question: I just read a few lines of this, and apparently: Numbers in JavaScript are "double-precision 64-bit format IEEE 754 values", according to the spec. This has some interesting consequences. There's no such thing as an integer in JavaScript, so you have to be a little careful with your arithmetic if you're used to math in C or Java. I've already seen that there are few of the data types (for variables) I'm used to from C++. But I didn't expect all numbers to automatically be floats. Isn't there any way to use integers, not float? Will a future version of JavaScript support ints?

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  • Operational Transformation library?

    - by gamers2000
    I'm looking for a library that would allow me to synchronize text in real-time between multiple users (ala Google Docs). I've stumbled upon Operational Transformation, which seems to fit my needs. Having said that, I understand the gist of OT, but not the math nor implementation of OT. Thus, I was wondering if there was a drag'n'drop Javascript library that would hook into a text area, generate the transforms, then allow me to apply those transformations onto another client? (I've gotten the Etherpad source, but I can't make head or tails out of it. If anyone could point out how to leverage on Etherpad's OT implementation, that'll be great too!)

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  • solr range query errors

    - by mquinsland
    http://localhost:8983/solr/select?wt=json&q=lat:[35%20to%2038] results in **org.apache.lucene.queryParser.ParseException: Cannot parse 'lat:[35 to 38]': Encountered " "38 "" at line 1, column 11. Was expecting: "]" This is a pretty basic range query and this error will prevent us from using SOLR for our projects

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  • Interesting AS3 hash situation. Is it really using strict equality as the documentation says?

    - by Triynko
    AS3 Code: import flash.utils.Dictionary; var num1:Number = Number.NaN; var num2:Number = Math.sqrt(-1); var dic:Dictionary = new Dictionary( true ); trace(num1); //NaN trace(num2); //NaN dic[num1] = "A"; trace( num1 == num2 ); //false trace( num1 === num2 ); //false trace( dic[num1] ); //A trace( dic[num2] ); //A Concerning the key comparison method... "The Dictionary class lets you create a dynamic collection of properties, which uses strict equality (===) for key comparison. When an object is used as a key, the object's identity is used to look up the object, and not the value returned from calling toString() on it." If Dictionary uses strict equality, as the documentation states, then how is it that num1 === num2 is false, and yet dic[num1] resolves to the same hash slot as dic[num2]?

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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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  • Is webserver bandwith the entire HTTP Request/Responce?

    - by Lienau
    Just a quick question. I'm making a web application where C++ communicates with a php script over HTTP Requests/Response. The data being set back and forth is quite small ~36 bytes. But I plan to have many computers connected, contacting the server quite often. I did the math, and I could potentially have gigabytes of data transfer a month. This isn't too much of problem, but it would be if the bandwidth included the request/response headers the request size would be about ~560 bytes. That's about 16x more bandwidth than I was planning... That would be a lot. If if any one knew how host determine bandwidth and could share, that'd be great. Thanks.

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