python Programming Glossary: byWhat is a metaclass in Python? http://stackoverflow.com/questions/100003/what-is-a-metaclass-in-python yourself. Since classes are objects they must be generated by something. When you use the class keyword Python creates this.. Python does when you use the keyword class and it does so by using a metaclass. What are metaclasses finally Metaclasses.. is just the class that creates class objects. You see that by checking the __class__ attribute. Everything and I mean everything..
The Python yield keyword explained http://stackoverflow.com/questions/231767/the-python-yield-keyword-explained When you create a list you can read its items one by one and it's called iteration mylist 1 2 3 for i in mylist ..... forget about it and calculate 1 and end calculating 4 one by one. Yield Yield is a keyword that is used like return except..
http://stackoverflow.com/questions/509211/pythons-slice-notation of the above a start end step # start through not past end by step The key point to remember is that the end value represents..
Python: How do I pass a variable by reference? http://stackoverflow.com/questions/986006/python-how-do-i-pass-a-variable-by-reference How do I pass a variable by reference The Python documentation seems unclear about whether.. seems unclear about whether parameters are passed by reference or value and the following code produces the unchanged.. 'Changed' Is there something I can do to pass the variable by actual reference python reference pass by reference share..
How to remove convexity defects in a Sudoku square? http://stackoverflow.com/questions/10196198/how-to-remove-convexity-defects-in-a-sudoku-square ConvexArea Mask All 2 largestComponent Image SortBy components First 1 2 By filling this image I get a mask for.. All 2 largestComponent Image SortBy components First 1 2 By filling this image I get a mask for the sudoku grid mask FillingTransform.. grid lines in the image verticalGridLineMasks SortBy ComponentMeasurements lX CaliperLength Centroid Mask # 100 All..
http://stackoverflow.com/questions/1035340/reading-binary-file-in-python byte # Do stuff with byte. byte f.read 1 finally f.close By suggestion of chrispy with open myfile rb as f byte f.read 1..
Choosing Java vs Python on Google App Engine http://stackoverflow.com/questions/1085898/choosing-java-vs-python-on-google-app-engine appengine java web will it play in app engine pli 1 Edit By power I mean better expandability and inclusion of available..
What does python sys.intern do, and when should it be used? http://stackoverflow.com/questions/1136826/what-does-python-sys-intern-do-and-when-should-it-be-used do pangolins dream of quiche' c is a False c is b False By using sys.intern you ensure that you never create two string..
How to efficiently calculate a running standard deviation? http://stackoverflow.com/questions/1174984/how-to-efficiently-calculate-a-running-standard-deviation 0.01788854 print nums.mean axis 1 # 0.022 0.018 0.02 0.02 By the way there's some interesting discussion in this blog post..
Local variables in Python nested functions http://stackoverflow.com/questions/12423614/local-variables-in-python-nested-functions at the time you call the function . Here lies the problem. By the time you call your functions the get_petters function is..
Does python have 'private' variables in classes? http://stackoverflow.com/questions/1641219/does-python-have-private-variables-in-classes you can get around Java's protections if you work at it . By the same convention the _ prefix means stay away even if you're..
In Python, how do I determine if an object is iterable? http://stackoverflow.com/questions/1952464/in-python-how-do-i-determine-if-an-object-is-iterable like a duck and quacks like a duck it must be a duck . By emphasizing interfaces rather than specific types well designed..
Can I use Python as a bash replacement? http://stackoverflow.com/questions/209470/can-i-use-python-as-a-bash-replacement in the shell with a few exceptions forks a subprocess. By using Python shutil and os modules you don't fork a subprocess...
The problem with installing PIL using virtualenv or buildout http://stackoverflow.com/questions/2485295/the-problem-with-installing-pil-using-virtualenv-or-buildout install no index f http dist.plone.org thirdparty U PIL By using pip install with the no index you avoid running the risk..
Why does Python print unicode characters when the default encoding is ASCII? http://stackoverflow.com/questions/2596714/why-does-python-print-unicode-characters-when-the-default-encoding-is-ascii various replies I think we can stitch up an explanation. By trying to print an unicode string u' xe9' Python implicitly..
Play a Sound with Python [duplicate] http://stackoverflow.com/questions/307305/play-a-sound-with-python What's the easiest way to play a sound file .wav in Python By easiest I mean both most platform independent and requiring..
How does Python's super() work with multiple inheritance? http://stackoverflow.com/questions/3277367/how-does-pythons-super-work-with-multiple-inheritance that's it the MRO would be Fourth Second Third First . By the way if Python cannot find a coherent method resolution order..
How can I download all emails with attachments from Gmail? http://stackoverflow.com/questions/348630/how-can-i-download-all-emails-with-attachments-from-gmail That was something. But try the same in Java just for fun By the way I tested that in a shell so some errors likely remain...
Suggestions for a Cron like scheduler in Python? http://stackoverflow.com/questions/373335/suggestions-for-a-cron-like-scheduler-in-python just jobs also written in Python python functions. By necessity I think this would be a different thread but not in..
What does `if __name__ == “__main__”:` do? http://stackoverflow.com/questions/419163/what-does-if-name-main-do it can also be imported and used in another module. By doing the main check you can have that code only execute when..
Python: Is there a way to determine the encoding of text file? http://stackoverflow.com/questions/436220/python-is-there-a-way-to-determine-the-encoding-of-text-file even though it is composed entirely of English letters . By studying lots of 𦭛ypical text a computer algorithm can simulate..
Accessing dict keys like an attribute in Python? http://stackoverflow.com/questions/4984647/accessing-dict-keys-like-an-attribute-in-python instance we are instantiating as we are in __init__ . By calling super 's __init__ method we made sure that it already..
How can I run an external command asynchronously from Python? http://stackoverflow.com/questions/636561/how-can-i-run-an-external-command-asynchronously-from-python run a shell command asynchronously from a Python script. By this I mean that I want my Python script to continue running..
Why is reading lines from stdin much slower in C++ than Python? http://stackoverflow.com/questions/9371238/why-is-reading-lines-from-stdin-much-slower-in-c-than-python readline getline share improve this question By default cin is synchronized with stdio which causes it to avoid..
Python Numpy Very Large Matrices http://stackoverflow.com/questions/1053928/python-numpy-very-large-matrices old laptop can crunch through data doing SQL like GROUP BY aggregation at 1 000 000 rows second. Not bad for a Python based..
http://stackoverflow.com/questions/108193/union-and-intersect-in-django s AND model_pk s tagged_item s.object_id GROUP BY model_pk s 'model_pk' ' s. s' model_table qn model._meta.pk.column.. s AND model_pk s tagged_item s.object_id GROUP BY model_pk s HAVING COUNT model_pk s tag_count s 'model_pk' '..
Pyparsing: extract variable length, variable content, variable whitespace substring http://stackoverflow.com/questions/10855951/pyparsing-extract-variable-length-variable-content-variable-whitespace-substr BILATERAL TUMOR QUANTITATION 15 OF PROSTATE INVOLVED BY TUMOR EXTRAPROSTATIC EXTENSION PRESENT AT RIGHT POSTERIOR.. PATTERN OF 5. TUMOR QUANTITATION APPROXIMATELY 10 BY VOLUME. TUMOR LOCATION BILATERAL. EXTRAPROSTATIC EXTENSION..
Parameter substitution for a SQLite “IN” clause http://stackoverflow.com/questions/1309989/parameter-substitution-for-a-sqlite-in-clause WHERE obfuscated_name IN Argl883 Manf496 Mook657 GROUP BY user_id python sqlite share improve this question You..
How do you make Python / PostgreSQL faster? http://stackoverflow.com/questions/136789/how-do-you-make-python-postgresql-faster all of the loads. Do a SELECT COUNT FROM whatever GROUP BY whatever and insert this into a table of counts. Don't Update...
Filter zipcodes by proximity in Django with the Spherical Law of Cosines http://stackoverflow.com/questions/1916953/filter-zipcodes-by-proximity-in-django-with-the-spherical-law-of-cosines lat AS distance FROM stores HAVING distance 25 ORDER BY distance LIMIT 0 20 The query needs to reference the Zipcode.. lat AS distance FROM stores HAVING distance 25 ORDER BY distance LIMIT 0 20 ids row 0 for row in cursor.fetchall return..
Convert datetime fields in Chrome history file (sqlite) to readable format http://stackoverflow.com/questions/2141537/convert-datetime-fields-in-chrome-history-file-sqlite-to-readable-format 11644473600 'unixepoch' 'localtime' url FROM urls ORDER BY last_visit_time DESC get_hist list cursor.execute sql_select..
http://stackoverflow.com/questions/2317452/django-count-rawqueryset WHERE price BETWEEN s AND s HAVING distance s ORDER BY distance ASC cars Car.objects.raw query lat lat lon min_price.. WHERE price BETWEEN s AND s HAVING distance s ORDER BY distance ASC cars Car.objects.raw query lat lat lon min_price..
How to insert arrays into a database? http://stackoverflow.com/questions/3738269/how-to-insert-arrays-into-a-database some measurement id AND `frame` some frame number ORDER BY `sensor_row` `sensor_col` And this will give you all the rows..
Django equivalent of COUNT with GROUP BY http://stackoverflow.com/questions/842031/django-equivalent-of-count-with-group-by equivalent of COUNT with GROUP BY I know Django 1.1 has some new aggregation methods. However.. query SELECT player_type COUNT FROM players GROUP BY player_type Is it possible with Django 1.1's Model Query API.. for inclusion only player_type field into GROUP BY clause. order_by for exclusion possible default ordering that..
http://stackoverflow.com/questions/9064018/how-to-debug-internal-error-current-transaction-is-aborted-commands-ignored-un . id WHERE tagging_taggeditem .content_type_id 11 GROUP BY tagging_tag .id tagging_tag .name ORDER BY tagging_tag .name..
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