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How to get all subsets of a set? (powerset)
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The Python itertools page has exactly a powerset recipe for this:
from itertools import chain, combinations
def powerset(iterable):
"powerset([1,2,3]) --> () (1,) (2,) (3,) (1,2) (1,3) (2,3) (1,2,3)"
s = list(iterabl...
What does enumerate() mean?
What does for row_number, row in enumerate(cursor): do in Python?
5 Answers
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Check if a Python list item contains a string inside another string
...bc-456'])
The test for iterable may not be the best. Got it from here: In Python, how do I determine if an object is iterable?
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Any way to properly pretty-print ordered dictionaries?
I like the pprint module in Python. I use it a lot for testing and debugging. I frequently use the width option to make sure the output fits nicely within my terminal window.
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What is a mixin, and why are they useful?
In " Programming Python ", Mark Lutz mentions "mixins". I'm from a C/C++/C# background and I have not heard the term before. What is a mixin?
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How does Django's Meta class work?
...For latest version of Django: Django docs: Model Meta options
Metaclass in Python:
The best description is here: What are metaclasses in Python?
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Check if an apt-get package is installed and then install it if it's not on Linux
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echo $?
sudo apt remove -y "$pkg"
dpkg -s "$pkg"
echo $?
ls -l /usr/lib/python3/dist-packages/certbot/reporter.py
sudo apt remove --purge certbot
dpkg -s "$pkg"
echo $?
ls -l /usr/lib/python3/dist-packages/certbot/reporter.py
then:
the first two echo $? output 0, only the third one outputs 1...
Parsing boolean values with argparse
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nargs='?' means zero or one argument. docs.python.org/3/library/argparse.html#nargs
– Maxim
Aug 3 '17 at 12:05
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Filter by property
...filters operate at the database level, generating SQL. To filter based on Python properties, you have to load the object into Python to evaluate the property--and at that point, you've already done all the work to load it.
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Batch Renaming of Files in a Directory
...asy way to rename a group of files already contained in a directory, using Python?
13 Answers
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