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How to initialize a two-dimensional array in Python?
I'm beginning python and I'm trying to use a two-dimensional list, that I initially fill up with the same variable in every place. I came up with this:
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n-grams in python, four, five, six grams?
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Great native python based answers given by other users. But here's the nltk approach (just in case, the OP gets penalized for reinventing what's already existing in the nltk library).
There is an ngram module that people seldom use in n...
Convert string to Python class object?
Given a string as user input to a Python function, I'd like to get a class object out of it if there's a class with that name in the currently defined namespace. Essentially, I want the implementation for a function which will produce this kind of result:
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How to escape os.system() calls?
... or any other kind of nasty shell metacharacter.
Update: If you are using Python 3.3 or later, use shlex.quote instead of rolling your own.
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Finding median of list in Python
How do you find the median of a list in Python? The list can be of any size and the numbers are not guaranteed to be in any particular order.
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Why use pip over easy_install? [closed]
...u can pip install ., pip install git+https://.
pip comes with the official Python 2.7 and 3.4+ packages from python.org, and a pip bootstrap is included by default if you build from source.
The various incomplete bits of documentation on installing, using, and building packages have been replaced by...
Create a dictionary with list comprehension
I like the Python list comprehension syntax.
14 Answers
14
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How do I raise the same Exception with a custom message in Python?
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Update: For Python 3, check Ben's answer
To attach a message to the current exception and re-raise it:
(the outer try/except is just to show the effect)
For python 2.x where x>=6:
try:
try:
raise ValueError # something...
Test if executable exists in Python?
In Python, is there a portable and simple way to test if an executable program exists?
21 Answers
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Counting the number of True Booleans in a Python List
...th the constant True, a simple sum is fine. However, keep in mind that in Python other values evaluate as True as well. A more robust solution would be to use the bool builtin:
>>> l = [1, 2, True, False]
>>> sum(bool(x) for x in l)
3
UPDATE: Here's another similarly robust so...