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Articles indexed Saturday March 27 2010

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  • In a digital photo, how can I detect if a mountain is obscured by clouds?

    - by Gavin Brock
    The problem I have a collection of digital photos of a mountain in Japan. However the mountain is often obscured by clouds or fog. What techniques can I use to detect that the mountain is visible in the image? I am currently using Perl with the Imager module, but open to alternatives. All the images are taken from the exact same position - these are some samples. My naïve solution I started by taking several horizontal pixel samples of the mountain cone and comparing the brightness values to other samples from the sky. This worked well for differentiating good image 1 and bad image 2. However in the autumn it snowed and the mountain became brighter than the sky, like image 3, and my simple brightness test started to fail. Image 4 is an example of an edge case. I would classify this as a good image since some of the mountain is clearly visible. UPDATE 1 Thank you for the suggestions - I am happy you all vastly over-estimated my competence. Based on the answers, I have started trying the ImageMagick edge-detect transform, which gives me a much simpler image to analyze. convert sample.jpg -edge 1 edge.jpg I assume I should use some kind of masking to get rid of the trees and most of the clouds. Once I have the masked image, what is the best way to compare the similarity to a 'good' image? I guess the "compare" command suited for this job? How do I get a numeric 'similarity' value from this?

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  • How do you use stereotype annotations in Spring 2.5.x?

    - by grigory
    When moving to Spring 2.5.x I found that it adds more stereotype annotations (on top of @Repository from 2.0): @Component, @Service and @Controller. How do you use them? Do you rely on implicit Spring support or you define custom stereotype specific functions/aspects/features? Or is it predominately for marking beans (compile time, conceptual, etc.)?

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  • How to find "\r" in a conditional?

    - by Werner
    Hi, in a C++ program some string reads info from file, and in some part contains a "\r" character. I need to remove it, afte the read, in order to avoid problems. I thought about comparing strings character to character, I thought that "\r" would take two chars, but not, it is just one. how would i use a conditional ? if char[4]==`\r' ??? Thanks P.D. How would the problem be solved in C?

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  • strtok wont accept: char *str

    - by bks
    strtok wont work correctly when using char *str as the first parameter (not the delimiters string). does it have something to do with the area that allocates strings in that notation? (which as far as i know, is a read-only area). thanks in advance example: //char* str ="- This, a sample string."; // <---doesn't work char str[] ="- This, a sample string."; // <---works char delims[] = " "; char * pch; printf ("Splitting string \"%s\" into tokens:\n",str); pch = strtok (str,delims); while (pch != NULL) { printf ("%s\n",pch); pch = strtok (NULL, delims); } return 0;

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  • how to redirect page if parameter set?

    - by Ronnie Chester Lynwood
    ey i want to make a thing but i need some help. ive got an index.php with codes. and i added "file" parameter to index.php. so i mean if "index.php?file=/folder/folder/picture.png" is set, download file. if "file=" not set do not do anything. I get "file" parameter with $_REQUEST thingy. please help thanks..

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  • Dynamic populate ComboBox (Flex)

    - by Vinzcent
    Hey, I want to populate a ComboBox after a clicked a button. This is my code: var dpNames:ArrayCollection = new ArrayCollection(); for each(var ca:Categorie in arrCategories) { dpNames.addItem ({label: ca.name, data: ca.value}); } cbWijzigCategorie.dataProvider = dpNames; But when he executes the last line, I alwas get the following error: TypeError: Error #1009: Cannot access a property or method of a null object reference. I have no idea why. Thanks a lot, Vincent

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  • Git: How do I rewind the Master branch on the remote origin

    - by user277260
    I made 5 commits to Master branch when bug hunting on a private project and pushed them to the remote origin (my own private vps). Then I saw that commits 4 and 5 were going to cause trouble elsewhere and I need to undo them, so I checked out commit 3 again, made a new branch "Dev" from that point, and did a few more commits fixing the issue properly. Then I did git reset --hard HEAD~2 on Master to pull it back to the point that I branched Dev. Then I did git merge to fast forward Master back to the end of the Dev branch. So now I have a local repository, with Dev and Master both pointing to the same, up to date version of the project with the latest bug fix. Problem is, when I try to push the project now to the origin, it fails and gives me an error message: ! [rejected] master - master (non-fast forward) error: failed to push some refs to 'myserver...myproject.git' What have I done wrong, and how do I fix it? Thanks

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  • Mac text/code editor

    - by Teifion
    I searched for this and found Maudite's question about text editors but they were all for Windows. As you have no doubt guessed, I am trying to find out if there are any text/code editors for the Mac besides what I know of. I'll edit my post to include editors listed. Free Textwrangler XCode and DashCode Mac Vim Smultron Aquamacs and closer to the original EMacs JEdit Editra Eclipse NetBeans Commercial Textmate BBEdit SubEthaEdit Coda Articles related to the subject Faceoff, which is the best text editor ever? Thank you everybody that has added suggestions, if I miss your suggestion then I'm sorry, I'm sure you can find me on Twitter or via Google.

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  • How can I read messages in a Gmail account from Perl?

    - by kiruthika
    I have used the module Mail::Webmail::Gmail to read the new messages in my Gmail account. I have written the following code for this purpose: use strict; use warnings; use Data::Dumper; use Mail::Webmail::Gmail; my $gmail = Mail::Webmail::Gmail->new( username => 'username', password => 'password', ); my $messages = $gmail->get_messages( label => $Mail::Webmail::Gmail::FOLDERS{ 'INBOX' } ); foreach ( @{ $messages } ) { if ( $_->{ 'new' } ) { print "Subject: " . $_->{ 'subject' } . " / Blurb: " . $_->{ 'blurb' } . "\n"; } } But it didn't print anything. Can anyone help me in this or suggest any other module for this? Thanks in advance.

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  • Interoperability between two AES algorithms

    - by lpfavreau
    Hello, I'm new to cryptography and I'm building some test applications to try and understand the basics of it. I'm not trying to build the algorithms from scratch but I'm trying to make two different AES-256 implementation talk to each other. I've got a database that was populated with this Javascript implementation stored in Base64. Now, I'm trying to get an Objective-C method to decrypt its content but I'm a little lost as to where the differences in the implementations are. I'm able to encrypt/decrypt in Javascript and I'm able to encrypt/decrypt in Cocoa but cannot make a string encrypted in Javascript decrypted in Cocoa or vice-versa. I'm guessing it's related to the initialization vector, nonce, counter mode of operation or all of these, which quite frankly, doesn't speak to me at the moment. Here's what I'm using in Objective-C, adapted mainly from this and this: @implementation NSString (Crypto) - (NSString *)encryptAES256:(NSString *)key { NSData *input = [self dataUsingEncoding: NSUTF8StringEncoding]; NSData *output = [NSString cryptoAES256:input key:key doEncrypt:TRUE]; return [Base64 encode:output]; } - (NSString *)decryptAES256:(NSString *)key { NSData *input = [Base64 decode:self]; NSData *output = [NSString cryptoAES256:input key:key doEncrypt:FALSE]; return [[[NSString alloc] initWithData:output encoding:NSUTF8StringEncoding] autorelease]; } + (NSData *)cryptoAES256:(NSData *)input key:(NSString *)key doEncrypt:(BOOL)doEncrypt { // 'key' should be 32 bytes for AES256, will be null-padded otherwise char keyPtr[kCCKeySizeAES256 + 1]; // room for terminator (unused) bzero(keyPtr, sizeof(keyPtr)); // fill with zeroes (for padding) // fetch key data [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding]; NSUInteger dataLength = [input length]; // See the doc: For block ciphers, the output size will always be less than or // equal to the input size plus the size of one block. // That's why we need to add the size of one block here size_t bufferSize = dataLength + kCCBlockSizeAES128; void* buffer = malloc(bufferSize); size_t numBytesCrypted = 0; CCCryptorStatus cryptStatus = CCCrypt(doEncrypt ? kCCEncrypt : kCCDecrypt, kCCAlgorithmAES128, kCCOptionECBMode | kCCOptionPKCS7Padding, keyPtr, kCCKeySizeAES256, nil, // initialization vector (optional) [input bytes], dataLength, // input buffer, bufferSize, // output &numBytesCrypted ); if (cryptStatus == kCCSuccess) { // the returned NSData takes ownership of the buffer and will free it on deallocation return [NSData dataWithBytesNoCopy:buffer length:numBytesCrypted]; } free(buffer); // free the buffer; return nil; } @end Of course, the input is Base64 decoded beforehand. I see that each encryption with the same key and same content in Javascript gives a different encrypted string, which is not the case with the Objective-C implementation that always give the same encrypted string. I've read the answers of this post and it makes me believe I'm right about something along the lines of vector initialization but I'd need your help to pinpoint what's going on exactly. Thank you!

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  • Opinions on collision detection objects with a moving scene

    - by Evan Teran
    So my question is simple, and I guess it boils down to how anal you want to be about collision detection. To keep things simple, lets assume we're talking about 2D sprites defined by a bounding box. In addition, let's assume that my sprite object has a function to detect collisions like this: S.collidesWith(other); Finally the scene is moving and "walls" in the scene can move, an object may not touch a wall. So a simple implementation might look like this (psuedo code): moveWalls(); moveSprite(); foreach(wall as w) { if(s.collidesWith(w)) { gameover(); } } The problem with this is that if the sprite and wall move towards each other, depending on the circumstances (such as diagonal moment). They may pass though each other (unlikely but could happen). So I may do this instead. moveWalls(); foreach(wall as w) { if(s.collidesWith(w)) { gameover(); } } moveSprite(); foreach(wall as w) { if(s.collidesWith(w)) { gameover(); } } This takes care of the passing through each other issue, but another rare issue comes up. If they are adjacent to each other (literally the next pixel) and both the wall and the sprite are moving left, then I will get an invalid collision since the wall moves, checks for collision (hit) then the sprite is moved. Which seems unfair. In addition, to that, the redundant collision detection feels very inefficient. I could give the player movement priority alleviating the first issue but it is still checking twice. moveSprite(); foreach(wall as w) { if(s.collidesWith(w)) { gameover(); } } moveWalls(); foreach(wall as w) { if(s.collidesWith(w)) { gameover(); } } Am I simply over thinking this issue, should this just be chalked up to "it'll happen rare enough that no one will care"? Certainly looking at old sprite based games, I often find situations where the collision detection has subtle flaws, but I figure by now we can do better :-P. What are people's thoughts?

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  • sharing news via twitter/facebook on ASP.NET

    - by Alexander
    I know this might have been asked a few times.. I have a news section in my site and I want to be able to share that news via facebook/twitter/buzz like the following: How can I do that? Is there a tutorial on how to implement these directly? facebook and twitter is the most important one

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  • What's the deal with all of the abstract stuff?

    - by JustVenting
    I see a lot of talk about MVVM, MVC, Design Patterns etc... You know, some guy has a blog, and he spent the last six months learning about one these things and desiging a program centered around that concept and then he goes on and on about it like its better than sliced bread. I read all of this crap and I wonder, whatever happened to simple logical programming? Not self-absorbed huge frameworks of design patterns and mvc and whatever else you can think of... just simple linear programming, perhaps a few classes to encapsulate things here and there.

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  • Get parent function

    - by Morgoth
    Is there a way to find what function called the current function? So for example: def first(): second() def second(): # print out here what function called this one Any ideas?

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  • Replaceing <a href="mailto: with just email aadress

    - by Lauri
    I want to replace all "mailto:" links in html with plain emails. In: text .... <a href="mailto:[email protected]">not needed</a> text Out: text .... [email protected] text I did this: $str = preg_replace("/\<a.+href=\"mailto:(.*)\".+\<\/a\>/", "$1", $str); But it fails if there are multiple emails in string or html inside "a" tag In: <a href="mailto:[email protected]">not needed</a><a href="mailto:[email protected]"><font size="3">[email protected]</font></a> Out: [email protected]">

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  • Speedup writing C programs using a subset of the Python syntax

    - by psihodelia
    I am constantly trying to optimize my time. Writing a C code takes a lot of time and requires much more keyboard touches than say writing a Python program. However, in order to speed up the time required to create a C program, one can automatize many things. I'd like to write my programs using smth. like Python but with C semantics. It means, all keywords are C keywords, but syntax is optimized. For example, this C code: #include "dsplib.h" #include "coeffs.h" #define MODULENAME "dsplib" #define NUM_SAMPLES 320 typedef float t_Vec; typedef struct s_Inter { char *pc_Name; struct s_Inter *px_Next; }t_Inter; typedef struct s_DspLibControl { t_Vec f_Y; }t_DspLibControl; void v_DspLibName(void) { printf("Module: %s", MODULENAME); printf("\n"); } int v_DspLibInitInterControl(t_DspLibControl *px_Con) { int y; px_Con->f_Y = 0.0; for(int i=0;i<10;i++) { y += i * i; } return y; } in optimized pythonized version can look like: include dsplib, coeffs define MODULENAME="dsplib", NUM_SAMPLES=320 typedef float t_Vec typedef struct s_Inter: char *pc_Name struct s_Inter *px_Next t_Inter typedef struct s_DspLibControl: t_Vec f_Y t_DspLibControl v_DspLibName(): printf("Module: %s", MODULENAME); printf("\n") int v_DspLibInitInterControl(t_DspLibControl *px_Con): int y px_Con->f_Y = 0.0 for int i=0;i<10;i++: y += i * i return y My question is: Do you know any VIM script, which allows to translate an original pythonized C code into a standard C code? For example, one is writing a C code but uses pythonized syntax, once she decides to translate pythonized blocks into standard C, she selects such blocks and press some key. And she doesn't save such pythonized code of course, VIM translates it into standard C.

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  • Why do people say that Ruby is slow?

    - by stephen murdoch
    I like Ruby on Rails and I use it for all my web development projects. A few years ago there was a lot of talk about Rails being a memory hog and about how it didn't scale very well but these suggestions were put to bed by Gregg Pollack here. Lately though, I've been hearing people saying that Ruby itself is slow. Why is Ruby considered slow? I do not find Ruby to be slow but then again, I'm just using it to make simple CRUD apps and company blogs. What sort of projects would I need to be doing before I find Ruby becoming slow? Or is this slowness just something that affects all programming languages? What are your options as a Ruby programmer if you want to deal with this "slowness"? Which version of Ruby would best suit an application like Stack Overflow where speed is critical and traffic is intense? The questions are subjective, and I realise that architectural setup (EC2 vs standalone servers etc) makes a big difference but I'd like to hear what people think about Ruby being slow. Finally, I can't find much news on Ruby 2.0 - I take it we're a good few years away from that then?

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  • ListView with Groups and CheckBoxes shows correctly only when View set to Details

    - by volody
    Microsoft MSDN site has next remark: "Any groups assigned to a ListView control appear whenever the ListView.View property is set to a value other than View.List." My problem is that i like to have View set to SmallIcon In this mode ListView control is shifted left, and CheckBoxes are covered by left edge How to solve this issue, or at least how is possible to shift rendering of control to the right

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