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Why `null >= 0 && null
I had to write a routine that increments the value of a variable by 1 if its type is number and assigns 0 to the variable if not, where the variable is initially null or undefined .
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What is a good regular expression to match a URL? [duplicate]
...ure URL starts with HTTP/HTTPS:
https?:\/\/(www\.)?[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()@:%_\+.~#?&//=]*)
If you do not require HTTP protocol:
[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()@:%_\+.~#?&//=]*)
To try this out see http://regex...
Fitting empirical distribution to theoretical ones with Scipy (Python)?
...an 30,000 integer values ranging from 0 to 47, inclusive, e.g. [0,0,0,0,..,1,1,1,1,...,2,2,2,2,...,47,47,47,...] sampled from some continuous distribution. The values in the list are not necessarily in order, but order doesn't matter for this problem.
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How can I plot with 2 different y-axes?
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update: Copied material that was on the R wiki at http://rwiki.sciviews.org/doku.php?id=tips:g...
What is the fastest integer division supporting division by zero no matter what the result is?
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107
Inspired by some of the comments I got rid of the branch on my Pentium and gcc compiler using
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Inline labels in Matplotlib
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mask = (xy[:,0] >= 0) & (xy[:,0] < N) & (xy[:,1] >= 0) & (xy[:,1] < N)
xy = xy[mask]
# add to pop
for p in xy:
pop[l][tuple(p)] = 1.0
# find whitespace, nice place for labels
ws = 1.0 - (np.sum(pop, axis=0) > 0) *...
Formula to determine brightness of RGB color
...ightness? Luminance?
Luminance (standard for certain colour spaces): (0.2126*R + 0.7152*G + 0.0722*B) [1]
Luminance (perceived option 1): (0.299*R + 0.587*G + 0.114*B) [2]
Luminance (perceived option 2, slower to calculate): sqrt( 0.241*R^2 + 0.691*G^2 + 0.068*B^2 ) → sqrt( 0.299*R^2 + 0.587*G^...
Fastest way to convert string to integer in PHP
Using PHP, what's the fastest way to convert a string like this: "123" to an integer?
8 Answers
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Checking for empty arrays: count vs empty
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12 Answers
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Efficient Algorithm for Bit Reversal (from MSB->LSB to LSB->MSB) in C
...reverse(register unsigned int x)
{
x = (((x & 0xaaaaaaaa) >> 1) | ((x & 0x55555555) << 1));
x = (((x & 0xcccccccc) >> 2) | ((x & 0x33333333) << 2));
x = (((x & 0xf0f0f0f0) >> 4) | ((x & 0x0f0f0f0f) << 4));
x = (((x & 0xf...