On 12/20/2010 10:49 PM, josef.p...@gmail.com wrote:
What's the difference between a numpy Random and a python
random.Random instance of separate states of the random number
generators?
Sorry, I don't understand the question. The difference
for my use is that a np.RandomState instance
I know this question came up on the mailing list some time ago
(19/09/2008), and the conclusion was that yes, you can do it more or
less efficiently in pure python; the trick is to use two different
methods. If your sample is more than, say, a quarter the size of the
set you're drawing from, you
We often need to generate more than one such sample from an array, e.g.
for permutation tests. If we shuffle an array x of size N and use x[:M] as
a random sample without replacement, we just need to put them back
randomly to get the next sample (cf. Fisher-Yates shuffle). That way we
get O(M)
I want to sample *without* replacement from a vector
(as with Python's random.sample). I don't see a direct
replacement for this, and I don't want to carry two
PRNG's around. Is the best way something like this?
permutation(myvector)[:samplesize]
Thanks,
Alan Isaac
I think this is not possible to do efficiently with just numpy. If you want
to do this efficiently, I wrote a no-replacement sampler in Cython some time
ago (below). I hearby release it to the public domain.
'''
Created on Oct 24, 2009
On Mon, Dec 20, 2010 at 11:28 AM, Alan G Isaac alan.is...@gmail.com wrote:
I want to sample *without* replacement from a vector
(as with Python's random.sample). I don't see a direct
replacement for this, and I don't want to carry two
PRNG's around. Is the best way something like this?
On 12/20/2010 9:41 PM, josef.p...@gmail.com wrote:
python has it in random
sample( population, k)
Yes, I mentioned this in my original post:
http://www.mail-archive.com/numpy-discussion@scipy.org/msg29324.html
But good simulation practice is perhaps to seed
a simulation specific random
On Mon, Dec 20, 2010 at 10:19 PM, Alan G Isaac alan.is...@gmail.com wrote:
On 12/20/2010 9:41 PM, josef.p...@gmail.com wrote:
python has it in random
sample( population, k)
Yes, I mentioned this in my original post:
http://www.mail-archive.com/numpy-discussion@scipy.org/msg29324.html
But
