reduce.py 文件源码

def _ireduce_ufunc_new_axis(arrays, ufunc, **kwargs):
    """
    Reduction operation for arrays, in the direction of a new axis (i.e. stacking).

    Parameters
    ----------
    arrays : iterable
        Arrays to be reduced.
    ufunc : numpy.ufunc
        Binary universal function. Must have a signature of the form ufunc(x1, x2, ...)
    kwargs
        Keyword arguments are passed to ``ufunc``.

    Yields 
    ------
    reduced : ndarray
    """
    arrays = iter(arrays)
    first = next(arrays)

    kwargs.pop('axis')

    dtype = kwargs.get('dtype', None)
    if dtype is None:
        dtype = first.dtype
    else:
        kwargs['casting'] = 'unsafe'

    # If the out parameter was already given
    # we create the accumulator from it
    # Otherwise, it is a copy of the first array
    accumulator = kwargs.pop('out', None)
    if accumulator is not None:
        accumulator[:] = first
    else:
        accumulator = np.array(first, copy = True).astype(dtype)
    yield accumulator

    for array in arrays:
        ufunc(accumulator, array, out = accumulator, **kwargs)
        yield accumulator