On Tue, Feb 10, 2009 at 11:29 AM, Mark Janikas <mjani...@esri.com> wrote:
> I want to create an array that contains a column of permutations for each
> simulation:
>
> import numpy as NUM
>
> import numpy.random as RAND
>
> x = NUM.arange(4.)
>
> res = NUM.zeros((4,100))
>
>
> for sim in range(100):
>
> res[:,sim] = RAND.permutation(x)
>
>
> Is there a way to do this without a loop? Thanks so much ahead of time…
Does this work? Might not be faster but it does avoid the loop.
import numpy as np
def weirdshuffle(nx, ny):
x = np.ones((nx,ny)).cumsum(0, dtype=np.int) - 1
yidx = np.ones((nx,ny)).cumsum(1, dtype=np.int) - 1
xidx = np.random.rand(nx,ny).argsort(0).argsort(0)
return x[xidx, yidx]
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