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Principal component analysis in Python
...
Months later, here's a small class PCA, and a picture:
#!/usr/bin/env python
""" a small class for Principal Component Analysis
Usage:
p = PCA( A, fraction=0.90 )
In:
A: an array of e.g. 1000 observations x 20 variables, 1000 rows x 20 colum...
Fastest way to get the first object from a queryset in django?
...eturn None if there aren't any. There are lots of ways to do this which all work. But I'm wondering which is the most performant.
...
Getting started with Haskell
...'ve done this by reading tutorials and watching screencasts, but nothing really seems to stick.
Now, in learning various imperative/OO languages (like C, Java, PHP), exercises have been a good way for me to go. But since I don't really know what Haskell is capable of and because there are many new c...
Exporting functions from a DLL with dllexport
...ain C exports, use a C project not C++. C++ DLLs rely on name-mangling for all the C++isms (namespaces etc...). You can compile your code as C by going into your project settings under C/C++->Advanced, there is an option "Compile As" which corresponds to the compiler switches /TP and /TC.
If you ...
Use numpy array in shared memory for multiprocessing
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To add to @unutbu's (not available anymore) and @Henry Gomersall's answers. You could use shared_arr.get_lock() to synchronize access when needed:
shared_arr = mp.Array(ctypes.c_double, N)
# ...
def f(i): # could be anything numpy accepts as an index such another numpy array
with ...
Obfuscated C Code Contest 2006. Please explain sykes2.c
...downwards). So, t is the character of __TIME__ being output.
a ends up equalling the following in binary, depending on the input t:
0 00111111
1 00101000
2 01110101
3 01111001
4 01101010
5 01011011
6 01011111
7 00101001
8 01111111
9 01111011
: 01000000
Each number is a bitmap describing the segm...
Django: How to completely uninstall a Django app?
What is the procedure for completely uninstalling a Django app, complete with database removal?
5 Answers
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One-liner to check whether an iterator yields at least one element?
... Similarly if you need to check if the iterator is empty, one could use all(False for _ in iterator) will check if the iterator is empty. (all returns True if the iterator is empty, otherwise it stops when it sees the first False element)
– KGardevoir
Apr 3 ...
Perforce for Git users? [closed]
...ou prefer Git you can use Git with Perforce quite well. We provide a tool called Git Fusion that generates Git repositories that are kept in sync with the Perforce server. Git and Perforce people can live in harmony working on the same code, mostly unaffected by their co-workers choice of version co...
How to sort two lists (which reference each other) in the exact same way
...s problem is to use the "decorate, sort, undecorate" idiom, which is especially simple using python's built-in zip function:
>>> list1 = [3,2,4,1, 1]
>>> list2 = ['three', 'two', 'four', 'one', 'one2']
>>> list1, list2 = zip(*sorted(zip(list1, list2)))
>>> list1
...