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Why is pow(a, d, n) so much faster than a**d % n?
... +1 that's actually what the docstring implies >>> print pow.__doc__ pow(x, y[, z]) -> number With two arguments, equivalent to x**y. With three arguments, equivalent to (x**y) % z, but may be more efficient (e.g. for longs).
– Hedde van der Heide
...
How do I check if a number evaluates to infinity?
...
if (result == Number.POSITIVE_INFINITY || result == Number.NEGATIVE_INFINITY)
{
// ...
}
You could possibly use the isFinite function instead, depending on how you want to treat NaN. isFinite returns false if your number is POSITIVE_INFINITY, NEGAT...
Stripping everything but alphanumeric chars from a string in Python
...ng.printable (part of the built-in string module). The use of compiled '[\W_]+' and pattern.sub('', str) was found to be fastest.
$ python -m timeit -s \
"import string" \
"''.join(ch for ch in string.printable if ch.isalnum())"
10000 loops, best of 3: 57.6 usec per loop
$ python -m tim...
Is it possible to forward-declare a function in Python?
...
in short, if you have if __name__ == '__main__': main() as the last line in your script everything will be just fine!
– Filipe Pina
Aug 3 '11 at 12:24
...
How do you create nested dict in Python?
...he following:
d = {} # can use defaultdict(dict) instead
for row in file_map:
# derive row key from something
# when using defaultdict, we can skip the next step creating a dictionary on row_key
d[row_key] = {}
for idx, col in enumerate(row):
d[row_key][idx] = col
Ac...
Programmatically generate video or animated GIF in Python?
...longer movies, use the streaming approach:
import imageio
with imageio.get_writer('/path/to/movie.gif', mode='I') as writer:
for filename in filenames:
image = imageio.imread(filename)
writer.append_data(image)
...
What is the Python equivalent of Matlab's tic and toc functions?
...) - t
I have a helper class I like to use:
class Timer(object):
def __init__(self, name=None):
self.name = name
def __enter__(self):
self.tstart = time.time()
def __exit__(self, type, value, traceback):
if self.name:
print('[%s]' % self.name,)
...
Removing duplicates from a list of lists
...;>> import itertools
>>> k.sort()
>>> list(k for k,_ in itertools.groupby(k))
[[1, 2], [3], [4], [5, 6, 2]]
itertools often offers the fastest and most powerful solutions to this kind of problems, and is well worth getting intimately familiar with!-)
Edit: as I mention in ...
How to prevent form resubmission when page is refreshed (F5 / CTRL+R)
... It seems to me that if you redirect to the same page, then $_POST is cleared. As I understand it, that was the desired effect. That was MY desired effect, anyway. I think the answer would be better if it made that explicit, though.
– donutguy640
...
.gitignore for Visual Studio Projects and Solutions
...l
# Build Results of an ATL Project
[Dd]ebugPS/
[Rr]eleasePS/
dlldata.c
*_i.c
*_p.c
*_i.h
*.ilk
*.meta
*.obj
*.pch
*.pdb
*.pgc
*.pgd
*.rsp
*.sbr
*.tlb
*.tli
*.tlh
*.tmp
*.tmp_proj
*.log
*.vspscc
*.vssscc
.builds
*.pidb
*.svclog
*.scc
# Chutzpah Test files
_Chutzpah*
# Visual C++ cache files
ipch...