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How to remove convexity defects in a Sudoku square?

... pixel with the result of a closing operation: src = ColorConvert[Import["http://davemark.com/images/sudoku.jpg"], "Grayscale"]; white = Closing[src, DiskMatrix[5]]; srcAdjusted = Image[ImageData[src]/ImageData[white]] The next step is to find the sudoku area, so I can ignore (mask out) the bac...
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Is gcc std::unordered_map implementation slow? If so - why?

...eUploader: { brandingHtml: "Powered by \u003ca href=\"https://imgur.com/\"\u003e\u003csvg class=\"svg-icon\" width=\"50\" height=\"18\" viewBox=\"0 0 50 18\" fill=\"none\" xmlns=\"http://www.w3.org/2000/svg\"\u003e\u003cpath d=\"M46.1709 9.17788C46.1709 8.26454 46.2665 7.94324 4...
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Unique fields that allow nulls in Django

...L for the purpose of uniqueness checks since ticket #9039 was fixed, see: http://code.djangoproject.com/ticket/9039 The issue here is that the normalized "blank" value for a form CharField is an empty string, not None. So if you leave the field blank, you get an empty string, not NULL, stored in t...
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How do I get the path to the current script with Node.js?

... So basically you can do this: fs.readFile(path.resolve(__dirname, 'settings.json'), 'UTF-8', callback); Use resolve() instead of concatenating with '/' or '\' else you will run into cross-platform issues. Note: __dirname is the l...
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Is the C# static constructor thread safe?

... { mutex.WaitOne(); return instance; } // Each call to Acquire() requires a call to Release() public static void Release() { mutex.ReleaseMutex(); } } share | ...
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Case insensitive searching in Oracle

... Since 10gR2, Oracle allows to fine-tune the behaviour of string comparisons by setting the NLS_COMP and NLS_SORT session parameters: SQL> SET HEADING OFF SQL> SELECT * 2 FROM NLS_SESSION_PARAMETERS 3 WHERE PARAMETER IN ('NLS_COMP', ...
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How to capture Curl output to a file?

...me to use the last segment of the URL path as the filename. Example: curl http://example.com/folder/big-file.iso -O will save the results to a new file named big-file.iso in the current folder. In this way it works similar to wget but allows you to specify other curl options that are not availabl...
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How to copy a row and insert in same table with a autoincrement field in MySQL?

....) select c1, c2, ... from your_table where id = 1 where c1, c2, ... are all the columns except id. If you want to explicitly insert with an id of 2 then include that in your INSERT column list and your SELECT: insert into your_table (id, c1, c2, ...) select 2, c1, c2, ... from your_table where i...
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open read and close a file in 1 line of code

... You don't really have to close it - Python will do it automatically either during garbage collection or at program exit. But as @delnan noted, it's better practice to explicitly close it for various reasons. So, what you can do to keep ...
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How can I append a string to an existing field in MySQL?

...ld to add full URL, ignoring null fields: UPDATE test SET image = CONCAT('https://my-site.com/images/',image) WHERE image IS NOT NULL; share | improve this answer | follow ...