scipy.stats.erlang¶

scipy.stats.erlang = <scipy.stats._continuous_distns.erlang_gen object at 0x7fbe1dba4350>[source]¶

An Erlang continuous random variable.

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:

Parameters:	x : array_like quantiles q : array_like lower or upper tail probability a : array_like shape parameters 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 is ‘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 = erlang(a, loc=0, scale=1) Frozen RV object with the same methods but holding the given shape, location, and scale fixed.

x : array_like

quantiles

q : array_like

lower or upper tail probability

a : array_like

shape parameters

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 is ‘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 = erlang(a, loc=0, scale=1)

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

See also

gamma

Notes

The Erlang distribution is a special case of the Gamma distribution, with the shape parameter a an integer. Note that this restriction is not enforced by erlang. It will, however, generate a warning the first time a non-integer value is used for the shape parameter.

Refer to gamma for examples.

Methods

`rvs(a, loc=0, scale=1, size=1)`	Random variates.
`pdf(x, a, loc=0, scale=1)`	Probability density function.
`logpdf(x, a, loc=0, scale=1)`	Log of the probability density function.
`cdf(x, a, loc=0, scale=1)`	Cumulative density function.
`logcdf(x, a, loc=0, scale=1)`	Log of the cumulative density function.
`sf(x, a, loc=0, scale=1)`	Survival function (1-cdf — sometimes more accurate).
`logsf(x, a, loc=0, scale=1)`	Log of the survival function.
`ppf(q, a, loc=0, scale=1)`	Percent point function (inverse of cdf — percentiles).
`isf(q, a, loc=0, scale=1)`	Inverse survival function (inverse of sf).
`moment(n, a, loc=0, scale=1)`	Non-central moment of order n
`stats(a, loc=0, scale=1, moments='mv')`	Mean(‘m’), variance(‘v’), skew(‘s’), and/or kurtosis(‘k’).
`entropy(a, loc=0, scale=1)`	(Differential) entropy of the RV.
`fit(data, a, loc=0, scale=1)`	Parameter estimates for generic data.
`expect(func, a, 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(a, loc=0, scale=1)`	Median of the distribution.
`mean(a, loc=0, scale=1)`	Mean of the distribution.
`var(a, loc=0, scale=1)`	Variance of the distribution.
`std(a, loc=0, scale=1)`	Standard deviation of the distribution.
`interval(alpha, a, loc=0, scale=1)`	Endpoints of the range that contains alpha percent of the distribution

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