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How can I multiply and divide using only bit shifting and adding?
...Hacker's Delight" by Henry S. Warren (ISBN 9780201914658).
The first idea for implementing division is to write the inverse value of the denominator in base two.
E.g.,
1/3 = (base-2) 0.0101 0101 0101 0101 0101 0101 0101 0101 .....
So,
a/3 = (a >> 2) + (a >> 4) + (a >> 6) + ... ...
Get Image size WITHOUT loading image into memory
...memory when calling .open. Looking at the docs of PIL 1.1.7, the docstring for .open says:
def open(fp, mode="r"):
"Open an image file, without loading the raster data"
There are a few file operations in the source like:
...
prefix = fp.read(16)
...
fp.seek(0)
...
but these hardly con...
How do I check if a string is valid JSON in Python?
In Python, is there a way to check if a string is valid JSON before trying to parse it?
4 Answers
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Sort a list by multiple attributes?
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For completeness from timeit: for me first gave 6 us per loop and the second 4.4 us per loop
– Brian Larsen
Feb 8 '13 at 21:52
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How do I list the symbols in a .so file
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The standard tool for listing symbols is nm, you can use it simply like this:
nm -gD yourLib.so
If you want to see symbols of a C++ library, add the "-C" option which demangle the symbols (it's far more readable demangled).
nm -gDC yourLib...
What does functools.wraps do?
...asking this question so that there will be a record of it on StackOverflow for future reference: what does functools.wraps do, exactly?
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What is the effect of extern “C” in C++?
...ration of your function. Your function definition is contained in a binary format (that was compiled by your C++ compiler) that the client C linker will then link to using the C name.
Since C++ has overloading of function names and C does not, the C++ compiler cannot just use the function name as a ...
Python ElementTree module: How to ignore the namespace of XML files to locate matching element when
...dle multiple namespaces and namespace aliases:
from io import StringIO # for Python 2 import from StringIO instead
import xml.etree.ElementTree as ET
# instead of ET.fromstring(xml)
it = ET.iterparse(StringIO(xml))
for _, el in it:
prefix, has_namespace, postfix = el.tag.partition('}')
if...
How can I swap positions of two open files (in splits) in vim?
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A bit late to the post, but came across this searching for something else. I wrote two functions awhile back to mark a window and then swap buffers between windows. This seems to be what you're asking for.
Just slap these in your .vimrc and map the functions how you see fit:...
How to calculate moving average using NumPy?
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If you just want a straightforward non-weighted moving average, you can easily implement it with np.cumsum, which may be is faster than FFT based methods:
EDIT Corrected an off-by-one wrong indexing spotted by Bean in the code. EDIT
def moving_averag...