On 23/04/07, Pierre GM pgmdevlist@gmail.com wrote:
Have you tried nonzero() ?
a[a<0] = numpy.random.normal(0,1)
will put a random number from the normal distribution where your initial a is negative. No Python loops needed, no Python temps.
When you say "no python temps" I guess you mean, no temporary *variables*? If I understand correctly, this allocates a temporary boolean array to hold the result of "a<0".
The double condition (0<a<1) is not legit. You should try logical.and(a>0,a<1) or (a>0) & (a<1)
Note the () around each condition in case #2.
This is an unfortunate limitation that comes from the fact that we can't override the behaviour of python's logical operations. a<b<c does the right thing for python scalars, but it does it by being expanded to (approximately) "a<b and b<c", and "and" doesn't do the right thing for arrays. The best we can do is override the bitwise operators for boolean arrays. This is a shame as I often want to select array elements that fall into a given range, and creating three temporary arrays instead of one is unpleasant.
Anne