SciPy

scipy.stats.kstwobign

scipy.stats.kstwobign = <scipy.stats._continuous_distns.kstwobign_gen object at 0x4d0bb10>[source]

Kolmogorov-Smirnov two-sided test for large N.

Continuous 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:

Parameters :

x : array_like

quantiles

q : array_like

lower or upper tail probability

loc : array_like, optional

location parameter (default=0)

scale : array_like, optional

scale parameter (default=1)

size : int or tuple of ints, optional

shape of random variates (default computed from input arguments )

moments : str, optional

composed of letters [‘mvsk’] specifying which moments to compute where ‘m’ = mean, ‘v’ = variance, ‘s’ = (Fisher’s) skew and ‘k’ = (Fisher’s) kurtosis. (default=’mv’)

Alternatively, the object may be called (as a function) to fix the shape, :

location, and scale parameters returning a “frozen” continuous RV object: :

rv = kstwobign(loc=0, scale=1) :

  • Frozen RV object with the same methods but holding the given shape, location, and scale fixed.

Examples :

——– :

>>> from scipy.stats import kstwobign :

>>> import matplotlib.pyplot as plt :

>>> fig, ax = plt.subplots(1, 1) :

Calculate a few first moments: :

>>> mean, var, skew, kurt = kstwobign.stats(moments=’mvsk’) :

Display the probability density function (``pdf``): :

>>> x = np.linspace(kstwobign.ppf(0.01), :

... kstwobign.ppf(0.99), 100) :

>>> ax.plot(x, kstwobign.pdf(x), :

... ‘r-‘, lw=5, alpha=0.6, label=’kstwobign pdf’) :

Alternatively, freeze the distribution and display the frozen pdf: :

>>> rv = kstwobign() :

>>> ax.plot(x, rv.pdf(x), ‘k-‘, lw=2, label=’frozen pdf’) :

Check accuracy of ``cdf`` and ``ppf``: :

>>> vals = kstwobign.ppf([0.001, 0.5, 0.999]) :

>>> np.allclose([0.001, 0.5, 0.999], kstwobign.cdf(vals)) :

True :

Generate random numbers: :

>>> r = kstwobign.rvs(size=1000) :

And compare the histogram: :

>>> ax.hist(r, normed=True, histtype=’stepfilled’, alpha=0.2) :

>>> ax.legend(loc=’best’, frameon=False) :

>>> plt.show() :

Methods

rvs(loc=0, scale=1, size=1) Random variates.
pdf(x, loc=0, scale=1) Probability density function.
logpdf(x, loc=0, scale=1) Log of the probability density function.
cdf(x, loc=0, scale=1) Cumulative density function.
logcdf(x, loc=0, scale=1) Log of the cumulative density function.
sf(x, loc=0, scale=1) Survival function (1-cdf — sometimes more accurate).
logsf(x, loc=0, scale=1) Log of the survival function.
ppf(q, loc=0, scale=1) Percent point function (inverse of cdf — percentiles).
isf(q, loc=0, scale=1) Inverse survival function (inverse of sf).
moment(n, loc=0, scale=1) Non-central moment of order n
stats(loc=0, scale=1, moments=’mv’) Mean(‘m’), variance(‘v’), skew(‘s’), and/or kurtosis(‘k’).
entropy(loc=0, scale=1) (Differential) entropy of the RV.
fit(data, loc=0, scale=1) Parameter estimates for generic data.
expect(func, loc=0, scale=1, lb=None, ub=None, conditional=False, **kwds) Expected value of a function (of one argument) with respect to the distribution.
median(loc=0, scale=1) Median of the distribution.
mean(loc=0, scale=1) Mean of the distribution.
var(loc=0, scale=1) Variance of the distribution.
std(loc=0, scale=1) Standard deviation of the distribution.
interval(alpha, loc=0, scale=1) Endpoints of the range that contains alpha percent of the distribution

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