CODEWITHSUNDEEP
pythonscipy
Vladimir Shabuniayeu
Vladimir Shabuniayeu

Reputation: 147

RVS in SCIPY Python

In scipy.stats most of distribution have rvs method, which provides random samples. But I didn't find explanation random samples of what? probability? No, because it more than 1.

Upvotes: 6

Views: 28980

Answers (1)

Bill Bell
Bill Bell

Reputation: 21663

By default, invoking an rvs method once produces a single value of a pseudorandom variable, not a pseudorandom sample. For instance, here we see the results of a series of invocations of the rvs method for the beta distribution with shape parameters 1 and 3.

>>> from scipy.stats import beta
>>> beta.rvs(1,3)
0.11573182734943342
>>> beta.rvs(1,3)
0.711001211281741
>>> beta.rvs(1,3)
0.13358246108665714

If it's necessary to repeat a series of pseudorandom values for this distribution then the random_state parameter can be used, as indicated here.

>>> beta.rvs(1,3,random_state=1)
0.2570633444085756
>>> beta.rvs(1,3)
0.006105422238509487
>>> beta.rvs(1,3)
0.03773135132269083
>>> beta.rvs(1,3,random_state=1)
0.2570633444085756
>>> beta.rvs(1,3)
0.006105422238509487
>>> beta.rvs(1,3)
0.03773135132269083

Clarification (I hope):

The full signature for beta.rvs is:

rvs(a, b, loc=0, scale=1, size=1, random_state=None)

When I first wrote that this method produces a single value of a pseudorandom variable, I should have indicated that this would be by default, since size=1. That is, the method produces a sample of size one by default. The method is obviously capable of producing larger (pseudo-)random samples by setting its size parameter to values greater than one.

Upvotes: 8

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