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How do I get the number of elements in a list?
...turns 3.
Explanation
Everything in Python is an object, including lists. All objects have a header of some sort in the C implementation.
Lists and other similar builtin objects with a "size" in Python, in particular, have an attribute called ob_size, where the number of elements in the object is...
How do I remove all .pyc files from a project?
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You are not quoting {}. What would happen if accidentally word-split and deleted an intermediate path which happens to be called like a fragment of the path you found?
– Robottinosino
Apr 3 '13 at 2:58
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Replacing a 32-bit loop counter with 64-bit introduces crazy performance deviations with _mm_popcnt_
...AMD documents it and compilers don't expose it.)
(Yes, these instructions all run on the same execution unit).
This dependency doesn't just hold up the 4 popcnts from a single loop iteration. It can carry across loop iterations making it impossible for the processor to parallelize different loop...
What is the id( ) function used for?
... Python objects.
Is it the same with memory addresses in C?
Conceptually, yes, in that they are both guaranteed to be unique in their universe during their lifetime. And in one particular implementation of Python, it actually is the memory address of the corresponding C object.
If yes, wh...
Format date and time in a Windows batch script
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All this can be done in just 2 lines using ordinary string replacement: stackoverflow.com/a/23558738/1879699
– Andreas
Apr 22 '16 at 9:34
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How do I create a constant in Python?
.... This is the closest equivalent to Java's final. However, it does not actually prevent reassignment:
from typing import Final
a: Final = 1
# Executes fine, but mypy will report an error if you run mypy on this:
a = 2
sha...
What's the best way to send a signal to all members of a process group?
... And if you modify the format slightly and sort, you get to see all processes nicely grouped and beginning with (potentially) the group parent in each group: ps x -o "%r %p %y %x %c" | sort -nk1,2
– haridsv
Dec 3 '12 at 12:18
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Absolute vs relative URLs
...ed Jan 5 '10 at 9:33
Daniel VassalloDaniel Vassallo
301k6666 gold badges475475 silver badges424424 bronze badges
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Running unittest with typical test directory structure
...on -m unittest test.test_antigravity.GravityTestCase.test_method
Running all tests:
You can also use test discovery which will discover and run all the tests for you, they must be modules or packages named test*.py (can be changed with the -p, --pattern flag):
$ cd new_project
$ python -m unitte...
what does the __file__ variable mean/do?
I usually just hard-wire these with the actual path. But there is a reason for these statements that determine path at runtime, and I would really like to understand the os.path module so that I can start using it.
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