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How to add an extra column to a NumPy array
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b = np.zeros((N,N+1))
b[:,:-1] = a
And timings:
In [23]: N = 10
In [24]: a = np.random.rand(N,N)
In [25]: %timeit b = np.hstack((a,np.zeros((a.shape[0],1))))
10000 loops, best of 3: 19.6 us per loop
In [27]: %timeit b = np.zeros((a.shape[0],a.shape[1]+1)); b[:,:-1] = a
100000 loops, best of ...
Extracting bits with a single multiplication
...don't need and put the ones we want in the right place.
Multiplication by 4 (00000100) would shift everything left by 2 and get you to a00b0000 . To get the b to move up we need to multiply by 1 (to keep the a in the right place) + 4 (to move the b up). This sum is 5, and combined with the earlier...
How to find list intersection?
...out duplicates then you can use set intersection:
>>> a = [1,2,3,4,5]
>>> b = [1,3,5,6]
>>> list(set(a) & set(b))
[1, 3, 5]
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What is the difference between Θ(n) and O(n)?
... community wiki
20 revs, 4 users 91%Mehrdad Afshari
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Converting int to bytes in Python 3
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edited Aug 17 '16 at 15:04
answered Jan 9 '14 at 10:37
Tim...
Using Linq to get the last N elements of a collection?
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429
collection.Skip(Math.Max(0, collection.Count() - N));
This approach preserves item order wit...
Overloading Macro on Number of Arguments
...FOO3(foo,bar,baz)
If you want a fourth one:
#define GET_MACRO(_1,_2,_3,_4,NAME,...) NAME
#define FOO(...) GET_MACRO(__VA_ARGS__, FOO4, FOO3, FOO2)(__VA_ARGS__)
FOO(a,b,c,d) # expeands to FOO4(a,b,c,d)
Naturally, if you define FOO2, FOO3 and FOO4, the output will be replaced by those o...
sed or awk: delete n lines following a pattern
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14
Note that the +N pattern is a GNU extension. Change the first n to an N in your second example to make it include the line with the pattern....
fastest MD5 Implementation in JavaScript
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edited Jul 30 '18 at 14:00
akmozo
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answered O...