fromnumeric.py 文件源码

def rank(a):
    """
    Return the number of dimensions of an array.

    If `a` is not already an array, a conversion is attempted.
    Scalars are zero dimensional.

    .. note::
        This function is deprecated in NumPy 1.9 to avoid confusion with
        `numpy.linalg.matrix_rank`. The ``ndim`` attribute or function
        should be used instead.

    Parameters
    ----------
    a : array_like
        Array whose number of dimensions is desired. If `a` is not an array,
        a conversion is attempted.

    Returns
    -------
    number_of_dimensions : int
        The number of dimensions in the array.

    See Also
    --------
    ndim : equivalent function
    ndarray.ndim : equivalent property
    shape : dimensions of array
    ndarray.shape : dimensions of array

    Notes
    -----
    In the old Numeric package, `rank` was the term used for the number of
    dimensions, but in Numpy `ndim` is used instead.

    Examples
    --------
    >>> np.rank([1,2,3])
    1
    >>> np.rank(np.array([[1,2,3],[4,5,6]]))
    2
    >>> np.rank(1)
    0

    """
    # 2014-04-12, 1.9
    warnings.warn(
        "`rank` is deprecated; use the `ndim` attribute or function instead. "
        "To find the rank of a matrix see `numpy.linalg.matrix_rank`.",
        VisibleDeprecationWarning)
    try:
        return a.ndim
    except AttributeError:
        return asarray(a).ndim