[Numpy-discussion] random number genration

Sturla Molden sturla@molden...
Tue Mar 29 09:49:05 CDT 2011


Den 29.03.2011 15:46, skrev Daniel Lepage:
>
> x = (np.random.random(size)<  p)

This will not work. A boolean array is not compactly stored, but an 
array of bytes. Only the first bit 0 is 1 with probability p, bits 1 to 
7 bits are 1 with probability 0. We thus have to do this 8 times for 
each byte, shift left by range(8), and combine them with binary or.  
Also the main use of random bits is crypto, which requires the use of 
/dev/urandom or CrypGenRandom instead of Mersenne Twister (np.random.rand).

Sturla


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