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  • Automatic tracking algorithm

    - by nico
    Hi everyone, I'm trying to write a simple tracking routine to track some points on a movie. Essentially I have a series of 100-frames-long movies, showing some bright spots on dark background. I have ~100-150 spots per frame, and they move over the course of the movie. I would like to track them, so I'm looking for some efficient (but possibly not overkilling to implement) routine to do that. A few more infos: the spots are a few (es. 5x5) pixels in size the movement are not big. A spot generally does not move more than 5-10 pixels from its original position. The movements are generally smooth. the "shape" of these spots is generally fixed, they don't grow or shrink BUT they become less bright as the movie progresses. the spots don't move in a particular direction. They can move right and then left and then right again the user will select a region around each spot and then this region will be tracked, so I do not need to automatically find the points. As the videos are b/w, I though I should rely on brigthness. For instance I thought I could move around the region and calculate the correlation of the region's area in the previous frame with that in the various positions in the next frame. I understand that this is a quite naïve solution, but do you think it may work? Does anyone know specific algorithms that do this? It doesn't need to be superfast, as long as it is accurate I'm happy. Thank you nico

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  • Reading Character from Image

    - by Chinjoo
    I am working on an application which requires matching of numbers from a scanned image file to database entry and update the database with the match result. Say I have image- employee1.jpg. This image will have two two handwritten entries - Employee number and the amount to be paid to the employee. I have to read the employee number from the image and query the database for the that number, update the employee with the amount to be paid as got from the image. Both the employee number and amount to be paid are written inside two boxes at a specified place on the image. Is there any way to automate this. Basically I want a solution in .net using c#. I know this can be done using artificial neural networks. Any ideas would be much appreciated.

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  • how to remove a few lines from a Unicode registry file using batch commands in Windows?

    - by Cosmin
    Hi. I have a program who's generating some data in registry. I save it with "reg export HKCU\Software\ProgramName\Data data.reg" (Unicode format). I need to take it to other computer and import it there so the program from that computer could use the data. But I have to remove some text lines from data.reg. The text lines are easy to find because they contain some strings. Now I'm doing this manually (using Wordpad) every few days but maybe there is another way... Oh and I can't install other programs on these computers (the access is restricted) so I have to use batch/cmd files. What I tried so far: - redirecting the export to "con" but is visual only not in a variable; - using "for /F ..." but this works only with ANSI and removes blank lines. Can somebody please help me...? Thank you.

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  • Finding a small image in a bigger one

    - by tur1ng
    Given an image with a large dimension ( 1.000 x 1.000). What is a good approach to find a small image (e.g. 50 x 50) in the big one? The smaller image can be rotated and differ in the size, but only with a 1:1 ratio. It's not related to any programming language - I'm just interested in pattern recognition. Thank you.

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  • Resize an array of images with OpenCV

    - by amr
    I'm passing an array of images (IplImage**) to an object in C++ using OpenCV. I'm then trying to iterate over that array and resize them all to a fixed size (150x150) I'm doing it this way: for(int i = 0; i< this->numTrainingFaces; i++) { IplImage* frame_copy = cvCreateImage( cvSize(150,150), this->faceImageArray[0]->depth, this->faceImageArray[0]->nChannels ); cout << "Created image" << endl; cvResize(this->faceImageArray[i], frame_copy); cout << "Resized image" << endl; IplImage* grey_image = cvCreateImage( cvSize( frame_copy->width, frame_copy->height ), IPL_DEPTH_8U, 1 ); cout << "Created grey image" << endl; cvCvtColor( frame_copy, grey_image, CV_RGB2GRAY ); cout << "Converted image" << endl; this->faceImageArray[i] = grey_image; cvReleaseImage(&frame_copy); cvReleaseImage(&grey_image); } But I'm getting this output, and I'm not sure why: Created image Resized image Created grey image Converted image Created image OpenCV Error: Assertion failed (src.type() == dst.type()) in cvResize, file /build/buildd/opencv-2.1.0/src/cv/cvimgwarp.cpp, line 3102 terminate called after throwing an instance of 'cv::Exception' what(): /build/buildd/opencv-2.1.0/src/cv/cvimgwarp.cpp:3102: error: (-215) src.type() == dst.type() in function cvResize Aborted I'm basically just trying to replace the image in the array with the resized one in as few steps as possible. Edit: Revised my code as follows: for(int i = 0; i< this->numTrainingFaces; i++) { IplImage* frame_copy = cvCreateImage( cvSize(150,150), this->faceImageArray[i]->depth, this->faceImageArray[i]->nChannels ); cvResize(this->faceImageArray[i], frame_copy); IplImage* grey_image = cvCreateImage( cvSize( frame_copy->width, frame_copy->height ), IPL_DEPTH_8U, 1 ); cvCvtColor( frame_copy, grey_image, CV_RGB2GRAY ); faceImageArray[i] = cvCreateImage( cvSize(grey_image->width, grey_image->height), grey_image->depth, grey_image->nChannels); cvCopy(grey_image,faceImageArray[i]); cvReleaseImage(&frame_copy); cvReleaseImage(&grey_image); } Then later on I'm performing some PCA, and get this output: OpenCV Error: Null pointer (Null pointer to the written object) in cvWrite, file /build/buildd/opencv-2.1.0/src/cxcore/cxpersistence.cpp, line 4740 But I don't think my code has got to the point where I'm explicitly calling cvWrite, so it must be part of the library. I can give a full implementation if necessary - is there anything in my code that's going to create a null pointer?

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  • Correct way to Convert 16bit PCM Wave data to float

    - by fredley
    I have a wave file in 16bit PCM form. I've got the raw data in a byte[] and a method for extracting samples, and I need them in float format, i.e. a float[] to do a Fourier Transform. Here's my code, does this look right? I'm working on Android so javax.sound.sampled etc. is not available. private static short getSample(byte[] buffer, int position) { return (short) (((buffer[position + 1] & 0xff) << 8) | (buffer[position] & 0xff)); } ... float[] samples = new float[samplesLength]; for (int i = 0;i<input.length/2;i+=2){ samples[i/2] = (float)getSample(input,i) / (float)Short.MAX_VALUE; }

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  • PHP Thumbnail image generator works, but consistently awaits 90% of its loadtime! Why?

    - by Sam
    Hi folks, This is the follow-up question from this general page load speed question. This question which will focus only, entirely and specifically on the thumbnail generator PHP code with the question: What's causing the 97% delays on these tiny thumbnails? Measuring only 3 ~ 5 kb each, this is strange indeed! Even after 7 orso bounty-rounds and 100 upvotes, the images are still doing nothing for over 97% of the time. It works allright, but it could be so much faster! ZAM, my pet robot, was so annoyed by not knowing why, he just pulled out some cords! Silly metal box... (I have asked permission from the original author, to put temporarily segments of the code online that I think could be the problem, after which I will remove all code, except the several lines that were the direct cause of this issue here to match the answer. This will be the free opportunity to perfect/speedup his otherwise already to my opinion vert versatile and userfriendly thumbnail generator.)

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  • recognizing text effect on an image for photoshop

    - by Shishant
    Hello, I had my site designed through an designer, I have this image from it, I want to use same kind of image for other navigation menus which I want to add now, my designer is not supplying me with psd`s of it. How can I know what text effects and fonts I should use in photoshop to achieve the same kind of result? Thank You.

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  • detect sender of signal (linux, ptrace)

    - by osgx
    Hello Can I distinguish signal, between delivered directly to a process and delivered via debugger. Case 1: $ ./process1 process1 (not ptraced) set up handler alarm(5); .... signal is handled and I can parse handler parameters Case 2: $ debugger1 ./process1 process1 (is ptraced by debugger1) set up handler alarm(5); ... signal is catched by debugger1. It resumes process1 with PTRACE_CONT, signal_number is 4th parameter of PTRACE_CONT. signal is redelivered to process1 it is handled. So, how can I detect in signal handler, was it redelivered by debugger or send by system? OS is Linux, kernel is 2.6.30. Programs are written in plain C.

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  • problem with background subtraction

    - by riyana
    I'm doing background subtraction using opencv. The problem is the foreground object is not always detected correctly. To deal with this I would like to use four or five images, and take their average as the background image. How can I do that?

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  • mean and variance of image in single pass

    - by ajith
    hi everyone,am trying to calculate mean and variance using 3X3 window over image(hXw) in opencv...here is my code...is there any accuracy issues with this??or is there any other efficient method to do it in one pass.? int pi,a,b; for(i=1;i

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  • How to solve the problem of not being informed of successful payments by the 3rd party system used b

    - by user68759
    I have a subscription based website that interacts with a 3rd party system to handle the payments. The steps to process a new subscriber registration are as follow: The subscriber enters his/her details in the subscription form and click on the submit button. Assuming the details specified are valid, a new record is created in the database to store these details. The subscriber is then redirected to the website of the 3rd party system (similar to paypal) to process the payment. Once the payment is succesful, the 3rd party website then redirect the subscriber back to our website. At this time, I know that the payment was succesful, so the record in the database is updated to indicate that payment has been made successfully. A problem that I have found occurring quite often is that if a subscriber pays but does not complete the process correctly (e.g. uses the back browser, closes the window), his/her record in the database doesn't get updated about this. Accordingly, I don't know if s/he has paid by just looking the record and need to wait for the report from the 3rd party system to find this out. How do you solve this problem? PS. One of the main reasons to store their details into the database before the payment process is done is so they can come back to complete the payment without re-entering their details again. For example, when their credit cards were rejected by the 3rd party system and they need to sort this out with their financial institution which may take a while.

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  • Would this method work to scale out SQL queries?

    - by David
    I have a database containing a single huge table. At the moment a query can take anything from 10 to 20 minutes and I need that to go down to 10 seconds. I have spent months trying different products like GridSQL. GridSQL works fine, but is using its own parser which does not have all the needed features. I have also optimized my database in various ways without getting the speedup I need. I have a theory on how one could scale out queries, meaning that I utilize several nodes to run a single query in parallel. The idea is to take an incoming SQL query and simply run it exactly like it is on all the nodes. When the results are returned to a coordinator node, the same query is run on the union of the resultsets. I realize that an aggregate function like average need to be rewritten into a count and sum to the nodes and that the coordinator divides the sum of the sums with the sum of the counts to get the average. What kinds of problems could not easily be solved using this model. I believe one issue would be the count distinct function. Edit: I am getting so many nice suggestions, but none have addressed the method.

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  • Fastest way to compute a "Visual" checksum of an image

    - by ensnare
    I'm looking to create an ID system for cataloging images. I can't use md5() since that will change if I alter the EXIF tags of the image. I am currently using the SHA1 checksum computed by imagemagick. It works perfectly, but it's really, really slow on larger images (~15 seconds on a quad-core xeon for a 21 megapixel JPG). Are there any other "visual" methods of uniquely identifying an image that would be faster? Thank you.

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  • Who do you use for a merchant account?

    - by Josh
    Hi everyone, I was hoping to get an idea of the merchant accounts out there and if there are any strong recommendations for one in particular. I would also appreciate advice on how merchant accounts differ. Please use separate answers for each recommendation so that we can take full advantage of the voting system. Thanks!

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  • parallel computation for an Iterator of elements in Java

    - by Brian Harris
    I've had the same need a few times now and wanted to get other thoughts on the right way to structure a solution. The need is to perform some operation on many elements on many threads without needing to have all elements in memory at once, just the ones under computation. As in, Iterables.partition is insufficient because it brings all elements into memory up front. Expressing it in code, I want to write a BulkCalc2 that does the same thing as BulkCalc1, just in parallel. Below is sample code that illustrates my best attempt. I'm not satisfied because it's big and ugly, but it does seem to accomplish my goals of keeping threads highly utilized until the work is done, propagating any exceptions during computation, and not having more than numThreads instances of BigThing necessarily in memory at once. I'll accept the answer which meets the stated goals in the most concise way, whether it's a way to improve my BulkCalc2 or a completely different solution. interface BigThing { int getId(); String getString(); } class Calc { // somewhat expensive computation double calc(BigThing bigThing) { Random r = new Random(bigThing.getString().hashCode()); double d = 0; for (int i = 0; i < 100000; i++) { d += r.nextDouble(); } return d; } } class BulkCalc1 { final Calc calc; public BulkCalc1(Calc calc) { this.calc = calc; } public TreeMap<Integer, Double> calc(Iterator<BigThing> in) { TreeMap<Integer, Double> results = Maps.newTreeMap(); while (in.hasNext()) { BigThing o = in.next(); results.put(o.getId(), calc.calc(o)); } return results; } } class SafeIterator<T> { final Iterator<T> in; SafeIterator(Iterator<T> in) { this.in = in; } synchronized T nextOrNull() { if (in.hasNext()) { return in.next(); } return null; } } class BulkCalc2 { final Calc calc; final int numThreads; public BulkCalc2(Calc calc, int numThreads) { this.calc = calc; this.numThreads = numThreads; } public TreeMap<Integer, Double> calc(Iterator<BigThing> in) { ExecutorService e = Executors.newFixedThreadPool(numThreads); List<Future<?>> futures = Lists.newLinkedList(); final Map<Integer, Double> results = new MapMaker().concurrencyLevel(numThreads).makeMap(); final SafeIterator<BigThing> it = new SafeIterator<BigThing>(in); for (int i = 0; i < numThreads; i++) { futures.add(e.submit(new Runnable() { @Override public void run() { while (true) { BigThing o = it.nextOrNull(); if (o == null) { return; } results.put(o.getId(), calc.calc(o)); } } })); } e.shutdown(); for (Future<?> future : futures) { try { future.get(); } catch (InterruptedException ex) { // swallowing is OK } catch (ExecutionException ex) { throw Throwables.propagate(ex.getCause()); } } return new TreeMap<Integer, Double>(results); } }

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  • Baffled by differences between WPF BitmapEncoders

    - by DanM
    I wrote a little utility class that saves BitmapSource objects to image files. The image files can be either bmp, jpeg, or png. Here is the code: public class BitmapProcessor { public void SaveAsBmp(BitmapSource bitmapSource, string path) { Save(bitmapSource, path, new BmpBitmapEncoder()); } public void SaveAsJpg(BitmapSource bitmapSource, string path) { Save(bitmapSource, path, new JpegBitmapEncoder()); } public void SaveAsPng(BitmapSource bitmapSource, string path) { Save(bitmapSource, path, new PngBitmapEncoder()); } private void Save(BitmapSource bitmapSource, string path, BitmapEncoder encoder) { using (var stream = new FileStream(path, FileMode.Create)) { encoder.Frames.Add(BitmapFrame.Create(bitmapSource)); encoder.Save(stream); } } } Each of the three Save methods work, but I get unexpected results with bmp and jpeg. Png is the only format that produces an exact reproduction of what I see if I show the BitmapSource on screen using a WPF Image control. Here are the results: BMP - too dark JPEG - too saturated PNG - correct Why am I getting completely different results for different file types? I should note that the BitmapSource in my example uses an alpha value of 0.1 (which is why it appears very desaturated), but it should be possible to show the resulting colors in any image format. I know if I take a screen capture using something like HyperSnap, it will look correct regardless of what file type I save to. Here's a HyperSnap screen capture saved as a bmp: As you can see, this isn't a problem, so there's definitely something strange about WPF's image encoders. Do I have a setting wrong? Am I missing something?

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  • Parallel For Loop - Problems when adding to a List - Possible .Net Bugs

    - by Kevin Crowell
    I am having some issues involving Parallel for loops and adding to a List. The problem is, the same code may generate different output at different times. I have set up some test code below. In this code, I create a List of 10,000 int values. 1/10th of the values will be 0, 1/10th of the values will be 1, all the way up to 1/10th of the values being 9. After setting up this List, I setup a Parallel for loop that iterates through the list. If the current number is 0, I add a value to a new List. After the Parallel for loop completes, I output the size of the list. The size should always be 1,000. Most of the time, the correct answer is given. However, I have seen 3 possible incorrect outcomes occur: The size of the list is less than 1,000 An IndexOutOfRangeException occurs @ doubleList.Add(0.0); An ArgumentException occurs @ doubleList.Add(0.0); The message for the ArgumentException given was: Destination array was not long enough. Check destIndex and length, and the array's lower bounds. What could be causing the errors? Is this a .Net bug? Is there something I can do to prevent this from happening? Please try the code for yourself. If you do not get an error, try it a few times. Please also note that you probably will not see any errors using a single-core machine. using System; using System.Collections.Generic; using System.Threading.Tasks; namespace ParallelTest { class Program { static void Main(string[] args) { List<int> intList = new List<int>(); List<double> doubleList = new List<double>(); for (int i = 0; i < 250; i++) { intList.Clear(); doubleList.Clear(); for (int j = 0; j < 10000; j++) { intList.Add(j % 10); } Parallel.For(0, intList.Count, j => { if (intList[j] == 0) { doubleList.Add(0.0); } }); if (doubleList.Count != 1000) { Console.WriteLine("On iteration " + i + ": List size = " + doubleList.Count); } } Console.WriteLine("\nPress any key to exit."); Console.ReadKey(); } } }

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  • Generate an image / thumbnail of a webpage using X/Gui-less linux

    - by dassouki
    There are a lot of solutions out there on generating a thumbnail or an image preview of a webpage. Some of these are websites like websnapshots, windows libraries such as PHP's imagegrabscreen (only works on windows), and KDE's wkhtml. Many more do exist. However, I'm looking for a GUI-less solution. Something I can create an API around and link it to php or python. I'm comfortable with python, php, C, and shell. This is a personal project, so I'm not interested in commercial applications as I'm aware of their existence. Any ideas?

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  • Image Resizing: Poor jpeg quality and black PNG backgrounds

    - by azz0r
    Hello, I have two issues with my class, basically the quality of the jpeg images is quite poor, but I'm not sure if thats down to my ratio resizing. Ideally I'd like this class to be strict with image sizes and crop into them, but I cant get my head around it. My main issue is that pngs always have a black bg, does anyone have experience with this happening? <?php class OpenSource_ImageResize { function __construct($theFile, $toWhere, $mime, $extension, $newWidth, $newHeight) { if ($mime == NULL) { $mime = getimagesize($theFile); $mime = $mime['mime']; } if ($mime == 'image/jpeg') { $size = getimagesize($theFile); if ($size[0] > $newWidth || $size[1] > $newHeight) { $sourceImage = imagecreatefromjpeg($theFile); } else { return copy($theFile, $toWhere); throw new exception('Could not create jpeg'); return false; } } else if ($mime == 'image/png') { $size = getimagesize($theFile); if ($size[0] > $newWidth || $size[1] > $newHeight) { $sourceImage = imagecreatefrompng($theFile); } else { return copy($theFile, $toWhere); //throw new exception('Could not create png'); return false; } } else if ($mime == 'image/gif') { $size = getimagesize($theFile); if ($size[0] > $newWidth || $size[1] > $newHeight) { $sourceImage = imagecreatefromgif ($theFile); } else { return copy($theFile, $toWhere); //throw new exception('Could not create gif'); return false; } } else { throw new exception('Not a valid mime type'); return false; } $oldX = imageSX($sourceImage); $oldY = imageSY($sourceImage); if ($newWidth == NULL) { $thumbHeight = $newHeight; $thumbWidth = round($newHeight/($oldY/$oldX)); } else if ($oldX > $oldY) { $thumbWidth = $newWidth; $thumbHeight = $oldY * ($newHeight/$oldX); } if ($oldX < $oldY) { $thumbWidth = round($newHeight/($oldY/$oldX)); $thumbHeight = $newHeight; } if ($oldX == $oldY) { $thumbWidth = $newWidth; $thumbHeight = $newHeight; } if (!gd_info()) { $dstImage = ImageCreate($thumbWidth, $thumbHeight); imagecopyresized($dstImage, $sourceImage, 0, 0, 0, 0, $thumbWidth, $thumbHeight, $oldX, $oldY); } else { $dstImage = ImageCreateTrueColor($thumbWidth, $thumbHeight); imagecopyresampled($dstImage, $sourceImage, 0, 0, 0, 0, $thumbWidth, $thumbHeight, $oldX, $oldY); } if ($mime == 'image/png') { $xparent = imagecolorresolvealpha($dstImage, 255,2,240, 0) ; imagecolortransparent($dstImage,$xparent); imagealphablending($dstImage,true); imagepng($dstImage, $toWhere); } else if ($mime == 'image/jpeg') { imagejpeg($dstImage, $toWhere); } else if ($mime == 'image/gif') { imagegif ($dstImage, $toWhere); } imagedestroy($dstImage); imagedestroy($sourceImage); return true; } }

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  • Java: Line appears when using AffineTransform to scale image

    - by Malakim
    Hi, I'm having a problem with image scaling. When I use the following code to scale an image it ends up with a line either at the bottom or on the right side of the image. double scale = 1; if (scaleHeight >= scaleWidth) { scale = scaleWidth; } else { scale = scaleHeight; } AffineTransform af = new AffineTransform(); af.scale(scale, scale); AffineTransformOp operation = new AffineTransformOp(af, AffineTransformOp.TYPE_NEAREST_NEIGHBOR); BufferedImage bufferedThumb = operation.filter(img, null); The original image is here: http://tinyurl.com/yzv6r7h The scaled image: http://tinyurl.com/yk6e8ga Does anyone know why the line appears? Thanks!

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  • Removing the transperancy from image while keeping the actual image

    - by KPL
    Hello people, I have three images,and , they are not square or rectangular in shape. They are just like face of anyone. So,basically, my images are in the size 196x196 or anything like that, but complete square or rectangle with the face in the middle and transperant background in the rest of the portion. Now, I want to remove the transperant background too and just keep the faces. Don't know if this is possible and mind you, this isn't a programming question.

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  • Technique to remove common words(and their plural versions) from a string

    - by Jake M
    I am attempting to find tags(keywords) for a recipe by parsing a long string of text. The text contains the recipe ingredients, directions and a short blurb. What do you think would be the most efficient way to remove common words from the tag list? By common words, I mean words like: 'the', 'at', 'there', 'their' etc. I have 2 methodologies I can use, which do you think is more efficient in terms of speed and do you know of a more efficient way I could do this? Methodology 1: - Determine the number of times each word occurs(using the library Collections) - Have a list of common words and remove all 'Common Words' from the Collection object by attempting to delete that key from the Collection object if it exists. - Therefore the speed will be determined by the length of the variable delims import collections from Counter delim = ['there','there\'s','theres','they','they\'re'] # the above will end up being a really long list! word_freq = Counter(recipe_str.lower().split()) for delim in set(delims): del word_freq[delim] return freq.most_common() Methodology 2: - For common words that can be plural, look at each word in the recipe string, and check if it partially contains the non-plural version of a common word. Eg; For the string "There's a test" check each word to see if it contains "there" and delete it if it does. delim = ['this','at','them'] # words that cant be plural partial_delim = ['there','they',] # words that could occur in many forms word_freq = Counter(recipe_str.lower().split()) for delim in set(delims): del word_freq[delim] # really slow for delim in set(partial_delims): for word in word_freq: if word.find(delim) != -1: del word_freq[delim] return freq.most_common()

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