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Drop unused factor levels in a subsetted data frame

...actor . When I create a subset of this dataframe using subset or another indexing function, a new data frame is created. However, the factor variable retains all of its original levels, even when/if they do not exist in the new dataframe. ...
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Parse a .py file, read the AST, modify it, then write back the modified source code

I want to programmatically edit python source code. Basically I want to read a .py file, generate the AST , and then write back the modified python source code (i.e. another .py file). ...
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Or versus OrElse

...oth terms. When temp Is DBNull.Value, it can't be compared to zero, so it falls over. You should use... well, whichever one makes sense. share | improve this answer | follow...
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error LNK2019: unresolved external symbol _WinMain@16 referenced in function ___tmainCRTStartup

... This worked only after I selected "all configurations" for both platform and type. Selecting "build" on the "Solution" attempted to build all and the first one tried was NOT the one had specified for console subsystem. – Joseph Stateson ...
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fs: how do I locate a parent folder?

... why? just generally why? can someone please explain? – eyurdakul May 16 '17 at 15:12 ...
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Code Golf: Lasers

...is sitting on top of now. Since the laser emitter is to be treated like a wall, set this to be a wall to begin with. if (tr/v<^/>v</) { my $o; $o .= "\n" while s/.$/$o .= $&, ""/meg; tr,/\\,\\/, for $o, $s; $_ = $o; } If the laser beam is pointing any way except right, rotate...
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Python multiprocessing pool.map for multiple arguments

...rmap method, which accepts a sequence of argument tuples. It then automatically unpacks the arguments from each tuple and passes them to the given function: import multiprocessing from itertools import product def merge_names(a, b): return '{} & {}'.format(a, b) if __name__ == '__main__':...
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Google Map API v3 — set bounds and center

...adow, icon: image, shape: shape, title: beach[0], zIndex: beach[3] }); bounds.extend(myLatLng); } map.fitBounds(bounds); } share | improve this answer |...
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Python (and Python C API): __new__ versus __init__

...vs immutable types. __new__ accepts a type as the first argument, and (usually) returns a new instance of that type. Thus it is suitable for use with both mutable and immutable types. __init__ accepts an instance as the first argument and modifies the attributes of that instance. This is inappropr...
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Ruby: require vs require_relative - best practice to workaround running in both Ruby =1.

...ernel def require_relative(path) require File.join(File.dirname(caller[0]), path.to_str) end end end This allows you to use require_relative as you would in ruby 1.9.2 in ruby 1.8 and 1.9.1. share ...