scipy tutorial - Baustatik-Info-Server

SciPy Reference Guide, Release 0.8.dev
binom
A binom discrete random variable.
Discrete random variables are defined from a standard form and may require some shape parameters to complete
its specification. Any optional keyword parameters can be passed to the methods of the RV object as given
below:
Examples
>>> import matplotlib.pyplot as plt
>>> numargs = binom.numargs
>>> [ n,pr ] = [’Replace with resonable value’,]*numargs
Display frozen pmf:
>>> rv = binom(n,pr)
>>> x = np.arange(0,np.min(rv.dist.b,3)+1)
>>> h = plt.plot(x,rv.pmf(x))
Check accuracy of cdf and ppf:
>>> prb = binom.cdf(x,n,pr)
>>> h = plt.semilogy(np.abs(x-binom.ppf(prb,n,pr))+1e-20)
Random number generation:
>>> R = binom.rvs(n,pr,size=100)
Custom made discrete distribution:
>>> vals = [arange(7),(0.1,0.2,0.3,0.1,0.1,0.1,0.1)]
>>> custm = rv_discrete(name=’custm’,values=vals)
>>> h = plt.plot(vals[0],custm.pmf(vals[0]))
Binomial distribution
Counts the number of successes in n independent trials when the probability of success each time
is pr.
binom.pmf(k,n,p) = choose(n,k)*p**k*(1-p)**(n-k) for k in {0,1,...,n}
614 Chapter 3. Reference