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bundles / numpy 2.4.4 / numpy / random / RandomState / chisquare

cython_function_or_method

numpy.random:RandomState.chisquare

Signature

def   chisquare ( df ,  size = None )

Summary

Draw samples from a chi-square distribution.

Extended Summary

When df independent random variables, each with standard normal distributions (mean 0, variance 1), are squared and summed, the resulting distribution is chi-square (see Notes). This distribution is often used in hypothesis testing.

Parameters

df : float or array_like of floats

Number of degrees of freedom, must be > 0.

size : int or tuple of ints, optional

Output shape. If the given shape is, e.g., (m, n, k), then m * n * k samples are drawn. If size is None (default), a single value is returned if df is a scalar. Otherwise, np.array(df).size samples are drawn.

Returns

out : ndarray or scalar

Drawn samples from the parameterized chi-square distribution.

Raises

: ValueError

When df <= 0 or when an inappropriate size (e.g. size=-1) is given.

Notes

The variable obtained by summing the squares of df independent, standard normally distributed random variables:

is chi-square distributed, denoted

The probability density function of the chi-squared distribution is

where is the gamma function,

Examples

np.random.chisquare(2,4)
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See also

random.Generator.chisquare

which should be used for new code.

Aliases

  • numpy.random.chisquare
  • numpy.random.RandomState.chisquare