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Fonction variation - module scipy.stats

Signature de la fonction variation

def variation(a, axis=0, nan_policy='propagate', ddof=0) 

Description

variation.__doc__

Compute the coefficient of variation.

    The coefficient of variation is the standard deviation divided by the
    mean.  This function is equivalent to::

        np.std(x, axis=axis, ddof=ddof) / np.mean(x)

    The default for ``ddof`` is 0, but many definitions of the coefficient
    of variation use the square root of the unbiased sample variance
    for the sample standard deviation, which corresponds to ``ddof=1``.

    Parameters
    ----------
    a : array_like
        Input array.
    axis : int or None, optional
        Axis along which to calculate the coefficient of variation. Default
        is 0. If None, compute over the whole array `a`.
    nan_policy : {'propagate', 'raise', 'omit'}, optional
        Defines how to handle when input contains nan.
        The following options are available (default is 'propagate'):

        * 'propagate': returns nan
        * 'raise': throws an error
        * 'omit': performs the calculations ignoring nan values

    ddof : int, optional
        Delta degrees of freedom.  Default is 0.

    Returns
    -------
    variation : ndarray
        The calculated variation along the requested axis.

    References
    ----------
    .. [1] Zwillinger, D. and Kokoska, S. (2000). CRC Standard
       Probability and Statistics Tables and Formulae. Chapman & Hall: New
       York. 2000.

    Examples
    --------
    >>> from scipy.stats import variation
    >>> variation([1, 2, 3, 4, 5])
    0.47140452079103173