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Code Issues Projects Releases Packages Wiki Activity Actions 11

Move binomialvariate() to a section for discrete distributions (GH-102955)

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Raymond Hettinger 2023-03-23 12:10:12 -05:00 • committed by GitHub
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commit 4695709143
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2 changed files with 28 additions and 23 deletions
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45
Lib/random.py
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@ -24,7 +24,6 @@
negative exponential
gamma
beta
binomial
pareto
Weibull
@ -33,6 +32,11 @@
circular uniform
von Mises
discrete distributions
----------------------
binomial
General notes on the underlying Mersenne Twister core generator:
* The period is 2**19937-1.
@ -731,6 +735,26 @@ class Random(_random.Random):
return y / (y + self.gammavariate(beta, 1.0))
return 0.0
def paretovariate(self, alpha):
"""Pareto distribution. alpha is the shape parameter."""
# Jain, pg. 495
u = 1.0 - self.random()
return u ** (-1.0 / alpha)
def weibullvariate(self, alpha, beta):
"""Weibull distribution.
alpha is the scale parameter and beta is the shape parameter.
"""
# Jain, pg. 499; bug fix courtesy Bill Arms
u = 1.0 - self.random()
return alpha * (-_log(u)) ** (1.0 / beta)
## -------------------- discrete distributions ---------------------
def binomialvariate(self, n=1, p=0.5):
"""Binomial random variable.
@ -816,25 +840,6 @@ class Random(_random.Random):
return k
def paretovariate(self, alpha):
"""Pareto distribution. alpha is the shape parameter."""
# Jain, pg. 495
u = 1.0 - self.random()
return u ** (-1.0 / alpha)
def weibullvariate(self, alpha, beta):
"""Weibull distribution.
alpha is the scale parameter and beta is the shape parameter.
"""
# Jain, pg. 499; bug fix courtesy Bill Arms
u = 1.0 - self.random()
return alpha * (-_log(u)) ** (1.0 / beta)
## ------------------------------------------------------------------
## --------------- Operating System Random Source ------------------