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• What's the fastest way to strip and replace a document of high unicode characters using Python?

  - by Rhubarb

  I am looking to replace from a large document all high unicode characters, such as accented Es, left and right quotes, etc., with "normal" counterparts in the low range, such as a regular 'E', and straight quotes. I need to perform this on a very large document rather often. I see an example of this in what I think might be perl here: http://www.designmeme.com/mtplugins/lowdown.txt Is there a fast way of doing this in Python without using s.replace(...).replace(...).replace(...)...? I've tried this on just a few characters to replace and the document stripping became really slow.

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• display browse dialog using matlab

  - by Acharf

  hey, I have created a blank GUI and now I want to program a push_button to display a browse dialog.

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• How do I use graythresh on an indexed image in MATLAB?

  - by user198729

  I = imread('coins.png'); level = graythresh(I); BW = im2bw(I,level); imshow(BW) The above is an example from the MATLAB documentation using a grayscale image. How can I make it work with an indexed image like in this post?

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• What is the "task" in twitter Storm parallelism

  - by John Wang

  I'm trying to learn twitter storm by following the great article "Understanding the parallelism of a Storm topology" However I'm a bit confused by the concept of "task". Is a task an running instance of the component(spout or bolt) ? A executor having multiple tasks actually is saying the same component is executed for multiple times by the executor, am I correct ? Moreover in a general parallelism sense, Storm will spawn a dedicated thread(executor) for a spout or bolt, but what is contributed to the parallelism by an executor(thread) having multiple tasks ? I think having multiple tasks in a thread, since a thread executes sequentially, only make the thread a kind of "cached" resource, which avoids spawning new thread for next task run. Am I correct? I may clear those confusion by myself after taking more time to investigate, but you know, we both love stackoverflow ;-) Thanks in advance.

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• What hash algorithms are paralellizable? Optimizing the hashing of large files utilizing on mult-co

  - by DanO

  I'm interested in optimizing the hashing of some large files (optimizing wall clock time). The I/O has been optimized well enough already and the I/O device (local SSD) is only tapped at about 25% of capacity, while one of the CPU cores is completely maxed-out. I have more cores available, and in the future will likely have even more cores. So far I've only been able to tap into more cores if I happen to need multiple hashes of the same file, say an MD5 AND a SHA256 at the same time. I can use the same I/O stream to feed two or more hash algorithms, and I get the faster algorithms done for free (as far as wall clock time). As I understand most hash algorithms, each new bit changes the entire result, and it is inherently challenging/impossible to do in parallel. Are any of the mainstream hash algorithms parallelizable? Are there any non-mainstream hashes that are parallelizable (and that have at least a sample implementation available)? As future CPUs will trend toward more cores and a leveling off in clock speed, is there any way to improve the performance of file hashing? (other than liquid nitrogen cooled overclocking?) or is it inherently non-parallelizable?

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• Understanding The Convolution Matrix

  - by Ryan Naddy

  I am learning about the Convolution Matrix, and I understand how they work, but I don't understand how to know before hand what the output of a Matrix will look like. For example lets say I want to add a blur to an image, I could guess 10,000+ different combinations of numbers before I get the correct one. I do know though that this formula will give me a blur effect, but I have no idea why. float[] sharpen = new float[] { 1/9f, 1/9f, 1/9f, 1/9f, 1/9f, 1/9f, 1/9f, 1/9f, 1/9f }; Can anyone either explain to me how this works or point me to some article, that explains this? I would like to know before hand what a possible output of the matrix will be without guessing. Basically I would like to know why do we put that number in the filed, and why not some other number?

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• how many processors can I get in a block on cuda GPU?

  - by Vickey

  hi all, I have two questions to ask 1) If I create only one block of threads in cuda and execute the my parallel program on it then is it possible that more than one processors would be given to single block so that my program get some benefit of multiprocessor platform ? 2) can I synchronize the threads of different blocks ? if yes please give some hints. Thanks in advance since I know I'll get replies as always I get.

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• MongoDB: What's the point of using MapReduce without parallelism?

  - by netvope

  Quoting http://www.mongodb.org/display/DOCS/MapReduce#MapReduce-Parallelism As of right now, MapReduce jobs on a single mongod process are single threaded Without parallelism, what are the benefits of MapReduce compared to simpler or more traditional methods for queries and data aggregation? To avoid confusion: the question is NOT "what are the benefits of document-oriented DB over traditional relational DB"

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• Which is the best algorithm to "Estimate and Visulize 2d skeleton using Opencv" from the drawn conto

  - by kumar

  Which is the best algorithm to "Estimate and Visulize 2d skeleton using Opencv" from the drawn contour Is the Recursive Centroid algorithm the Best? any reference links or docs please provide

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• .NET: How to ignore comments when reading a XML file into a XmlDocument?

  - by tunnuz

  Hello, I am trying to read a XML document with C#, I am doing it this way: XmlDocument myData = new XmlDocument(); myData.Load("datafile.xml"); anyway, I sometimes get comments when reading XmlNode.ChildNodes. Is there a way to avoid that? I know that you can avoid reading comments if you use XmlReader, but then, how to get the XmlDocument out of a XmlReader? Thank you Tommaso

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• Edit axes to an image in matlab ?

  - by ZaZu

  Hello, I would like to edit the axes in my series of images being displayed .. This is how my image looks like : As you can see, it starts from 0 to ~~500 from top to bottom, can I invert that ? Plus I want to mirror the image being shown, so that it starts from left to right ... Or if its possible, let the axes show from right to left ? Thanks !

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• Finding many local max in an image (using MatLab)

  - by wenh42

  How do you go about figuring our multiple max in a 2D image where the max aren't necessarily all the same height? I have found that the imregionalmax(), imextendedmax(), and findpeaks() functions aren't necessarily that helpful because they give many local max that are really just maxes within the background noise. I tried bw=arrayimdilate(array,[1 1 1; 1 0 1; 1 1 1]) but that also is kind of limited for the same reasons (same thing with expanding the matrix that it uses). I'd definitely appreciate some help..

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• How to printf a time_t variable as a floating point number?

  - by soneangel

  Hi guys, I'm using a time_t variable in C (openMP enviroment) to keep cpu execution time...I define a float value sum_tot_time to sum time for all cpu's...I mean sum_tot_time is the sum of cpu's time_t values. The problem is that printing the value sum_tot_time it appear as an integer or long, by the way without its decimal part! I tried in these ways: to printf sum_tot_time as a double being a double value to printf sum_tot_time as float being a float value to printf sum_tot_time as double being a time_t value to printf sum_tot_time as float being a time_t value Please help me!!

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• How to make disconnected closed curves connected by adding a shortest path using MATLAB?

  - by user198729

  bwlabel can be used to get disconnected objects in an image: [L Ne] = bwlabel(image); I want to make the objects(But my target is only the contours(closed curve) of these objects) connected by adding a shortest path where necessary. How do I approach this? UPDATE Or how to dilate the closed curves so that they get connected? How to calculate the shortest path between two disconnected closed curves?

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• On-the-fly thumbnails PHP

  - by Wayne

  I came up with this: <?php $dir = $_GET['dir']; header('Content-type: image/jpeg'); $create = imagecreatetruecolor(150, 150); $img = imagecreatefromjpeg($dir); imagecopyresampled($create, $img, 0, 0, 0, 0, 150, 150, 150, 150); imagejpeg($create, null, 100); ?> It works by accessing: http://domain.com/image.php?dir=thisistheimage.jpg Which works fine... but the output is awful: Can someone fix my code for the image to be 150 x 150 covering the black area... Thanks.

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• What is a good way of Enhancing contrast of color images?

  - by erjik

  I split color image for 3 channels and made a contrast enhancement of each channel. Then merged them together, I like the image at the result, but it has different colors. Black objects became yellow and so on... EDIT: The algorithm I used is to calculate the 5th percentile and the 95th percentile as min and max values, and then expand the values of image so that it will have min and max values as 0 and 255. If there is a better approach please tell me.

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• head detection from video

  - by Aman Kaushal

  I have to detect heads of people in crowd in real time.For that I detected edge from video using matlab but from edge detected video , how to identify heads that i am unable to do. I used edge detection of video because it is easy to find circle from edged video and detection of head would be easy can anyone help me or suggest me any method for head- detection in real time. I have used VGG head detector and viola jones algorithm but it is only detecting face for small size video not detecting heads for large crowd. Suggestions?

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• Can I process video using flash?

  - by Roman

  I want to have a web page where user can activate his/her web-camera and send video to another user. Additionally to that I want to have a possibility to process video on the client side. In more details, I want to have a program which analyze video on the client side. Is it possible to do it with Flash?

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• flip a 1bpp .bmp image horizontally

  - by user576844

  I am trying to write a program containing two source files: main program written in C and assembly(x86 32 and 64) module callable from C. The C declaration for the assembly routine looks like this: void mirrorbmp1(void *img, int width, int height) The task involves Mirror/flipping a 1 bpp .BMP image horizontally while Handling any image width properly, not only multiples of 8. I am new to assembly programming and have very little idea about how i should do the ask. Any help would be appreciated.

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• "A generic error occurred in GDI+" error while showing uploaded images

  - by Prasad

  i am using the following code to show the image that has been saved in my database from my asp.net mvc(C#) application:. public ActionResult GetSiteHeaderLogo() { SiteHeader _siteHeader = new SiteHeader(); Image imgImage = null; long userId = Utility.GetUserIdFromSession(); if (userId > 0) { _siteHeader = this.siteBLL.GetSiteHeaderLogo(userId); if (_siteHeader.Logo != null && _siteHeader.Logo.Length > 0) { byte[] _imageBytes = _siteHeader.Logo; if (_imageBytes != null) { using (System.IO.MemoryStream imageStream = new System.IO.MemoryStream(_imageBytes)) { imgImage = Image.FromStream(imageStream); } } string sFileExtension = _siteHeader.FileName.Substring(_siteHeader.FileName.IndexOf('.') + 1, _siteHeader.FileName.Length - (_siteHeader.FileName.IndexOf('.') + 1)); Response.ContentType = Utility.GetContentTypeByExtension(sFileExtension.ToLower()); Response.Cache.SetCacheability(HttpCacheability.NoCache); Response.BufferOutput = false; if (imgImage != null) { ImageFormat _imageFormat = Utility.GetImageFormat(sFileExtension.ToLower()); imgImage.Save(Response.OutputStream, _imageFormat); imgImage.Dispose(); } } } return new EmptyResult(); } It works fine when i upload original image. But when i upload any downloaded images, it throws the following error: System.Runtime.InteropServices.ExternalException: A generic error occurred in GDI+. System.Runtime.InteropServices.ExternalException: A generic error occurred in GDI+. at System.Drawing.Image.Save(Stream stream, ImageCodecInfo encoder, EncoderParameters encoderParams) at System.Drawing.Image.Save(Stream stream, ImageFormat format) For. Ex: When i upload the original image, it shows as logo in my site and i downloaded that logo from the site and when i re-upload the same downloaded image, it throws the above error. It seems very weird to me and not able to find why its happening. Any ideas on this?

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• How to write efficient code for extracting Noun phrases?

  - by Arun Abraham

  I am trying to extract phrases using rules such as the ones mentioned below on text which has been POS tagged 1) NNP - NNP (- indicates followed by) 2) NNP - CC - NNP 3) VP - NP etc.. I have written code in this manner, Can someone tell me how i can do in a better manner. List<String> nounPhrases = new ArrayList<String>(); for (List<HasWord> sentence : documentPreprocessor) { //System.out.println(sentence.toString()); System.out.println(Sentence.listToString(sentence, false)); List<TaggedWord> tSentence = tagger.tagSentence(sentence); String lastTag = null, lastWord = null; for (TaggedWord taggedWord : tSentence) { if (lastTag != null && taggedWord.tag().equalsIgnoreCase("NNP") && lastTag.equalsIgnoreCase("NNP")) { nounPhrases.add(taggedWord.word() + " " + lastWord); //System.out.println(taggedWord.word() + " " + lastWord); } lastTag = taggedWord.tag(); lastWord = taggedWord.word(); } } In the above code, i have done only for NNP followed by NNP extraction, how can i generalise it so that i can add other rules too. I know that there are libraries available for doing this , but wanted to do this manually.

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• Thresholding in Matlab

  - by 3babala

  How do I threshold an image to find the local maxes in a robust way? I know I can just look at the data, visually guess at some appropriate h value, and do imextendedmax(I,h) where h is the threshold... but I'm looking for a more robust way to do it in Matlab. I'm pretty new to Matlab and coding so this is all foreign...

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• Parallel software?

  - by mavric

  What is the meaning of "parallel software" and what are the differences between "parallel software" and "regular software"? What are its advantages and disadvantages? Does writing "parallel software" require a specific hardware or programming language ?

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• Embarrassingly parallel workflow creates too many output files

  - by Hooked

  On a Linux cluster I run many (N > 10^6) independent computations. Each computation takes only a few minutes and the output is a handful of lines. When N was small I was able to store each result in a separate file to be parsed later. With large N however, I find that I am wasting storage space (for the file creation) and simple commands like ls require extra care due to internal limits of bash: -bash: /bin/ls: Argument list too long. Each computation is required to run through a qsub scheduling algorithm so I am unable to create a master program which simply aggregates the output data to a single file. The simple solution of appending to a single fails when two programs finish at the same time and interleave their output. I have no admin access to the cluster, so installing a system-wide database is not an option. How can I collate the output data from embarrassingly parallel computation before it gets unmanageable?

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• CUDA small kernel 2d convolution - how to do it

  - by paulAl

  I've been experimenting with CUDA kernels for days to perform a fast 2D convolution between a 500x500 image (but I could also vary the dimensions) and a very small 2D kernel (a laplacian 2d kernel, so it's a 3x3 kernel.. too small to take a huge advantage with all the cuda threads). I created a CPU classic implementation (two for loops, as easy as you would think) and then I started creating CUDA kernels. After a few disappointing attempts to perform a faster convolution I ended up with this code: http://www.evl.uic.edu/sjames/cs525/final.html (see the Shared Memory section), it basically lets a 16x16 threads block load all the convolution data he needs in the shared memory and then performs the convolution. Nothing, the CPU is still a lot faster. I didn't try the FFT approach because the CUDA SDK states that it is efficient with large kernel sizes. Whether or not you read everything I wrote, my question is: how can I perform a fast 2D convolution between a relatively large image and a very small kernel (3x3) with CUDA?

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