The following code: Is generating the following error message: I looked up the syntax at this link and I seem to be using the correct syntax to slice. However, when I type into the Python shell, it gives me the following output, which is clearly wrong, and is probably what is throwing the error: Can anyone sh…
Tag: python
Convert Python program to C/C++ code? [closed]
Closed. This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed 4 months ago. Improve this question is it possible to convert a Python program to C/C++? I need to implement …
How do I reverse a part (slice) of a list in Python?
Why doesn’t this work? Answer a[2:4] creates a copy of the selected sublist, and this copy is reversed by a[2:4].reverse(). This does not change the original list. Slicing Python lists always creates copies — you can use to copy the whole list.
How to construct a timedelta object from a simple string
I’m writing a function that needs to parse string to a timedelta. The user must enter something like “32m” or “2h32m”, or even “4:13” or “5hr34m56s”… Is there a library or something that has this sort of thing already implemented? Answer For the firs…
In Python try until no error
I have a piece of code in Python that seems to cause an error probabilistically because it is accessing a server and sometimes that server has a 500 internal server error. I want to keep trying until I do not get the error. My solution was: This seems like a hack to me. Is there a more Pythonic way to
Find indices of elements equal to zero in a NumPy array
NumPy has the efficient function/method nonzero() to identify the indices of non-zero elements in an ndarray object. What is the most efficient way to obtain the indices of the elements that do have a value of zero? Answer numpy.where() is my favorite. The method where returns a tuple of ndarrays, each corres…
Connecting slots and signals in PyQt4 in a loop
Im trying to build a calculator with PyQt4 and connecting the ‘clicked()’ signals from the buttons doesn’t work as expected. Im creating my buttons for the numbers inside a for loop where i try to connect them afterwards. When I click on the buttons all of them print out ‘9’. Why…
Convert [key1,val1,key2,val2] to a dict?
Let’s say I have a list a in Python whose entries conveniently map to a dictionary. Each even element represents the key to the dictionary, and the following odd element is the value for example, and I’d like to convert it to a dictionary b, where What is the syntactically cleanest way to accompli…
Get selected subcommand with argparse
When I use subcommands with python argparse, I can get the selected arguments. So args doesn’t contain ‘foo’. Simply writing sys.argv[1] doesn’t work because of the possible global args. How can I get the subcommand itself? Answer The very bottom of the Python docs on argparse sub-comm…
about Speed: Python VS Java
Just curious about speed of Python and Java.. Intuitively, Python should be much slower than java, but I want to know more…Could anybody give me more? or introduce some nice post to read? Answer The current standard implementation of Python (CPython) is slower than Java because the standard CPython impl…