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Why can't I use a list as a dict key in python?
..., with the hash as, say, their memory location?
It can be done without really breaking any of the requirements, but it leads to unexpected behavior. Lists are generally treated as if their value was derived from their content's values, for instance when checking (in-)equality. Many would - underst...
Count the number occurrences of a character in a string
...e counts for a lot of the letters in a given string, Counter provides them all in a more succinct form. If you want the count for one letter from a lot of different strings, Counter provides no benefit.
– Brenden Brown
Feb 17 '15 at 19:30
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How do I create an average from a Ruby array?
...void integer division or your results will be wrong. Also, this isn't generally applicable to every possible element type (obviously, an average only makes sense for things that can be averaged). But if you want to go that route, use this:
class Array
def sum
inject(0.0) { |result, el| result...
How to determine the version of the C++ standard used by the compiler?
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By my knowledge there is no overall way to do this. If you look at the headers of cross platform/multiple compiler supporting libraries you'll always find a lot of defines that use compiler specific constructs to determine such things:
/*Define Microsoft V...
Can modules have properties the same way that objects can?
...s? When I put this code in one file x.py and import it from another, then calling x.y results in AttributeError: 'NoneType' object has no attribute 'c', since _M somehow has value None...
– Stephan202
May 19 '09 at 1:35
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Where is my Django installation?
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Current top (accepted) answer works with my Ubuntu installation. As does yours. As do all of them!
– Adam Marshall
Apr 28 '14 at 14:24
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Naming convention - underscore in C++ and C# variables
... in a class field. What does the underscore mean? Is there a reference for all these special naming conventions?
19 Answers...
Finding the index of an item in a list
... complete. Some caveats about list.index follow. It is probably worth initially taking a look at the documentation for it:
list.index(x[, start[, end]])
Return zero-based index in the list of the first item whose value is equal to x. Raises a ValueError if there is no such item.
The optional argum...
Casting vs using the 'as' keyword in the CLR
...d within the if body.) That's slightly annoying in some cases, so if you really care about introducing the smallest number of variables possible in every scope, you might still want to use is followed by a cast.
I don't think any of the answers so far (at the time of starting this answer!) have r...
Does use of final keyword in Java improve the performance?
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Usually not. For virtual methods, HotSpot keeps track of whether the method has actually been overridden, and is able to perform optimizations such as inlining on the assumption that a method hasn't been overridden - until it lo...