core.py 文件源码

def _cartesian_product(*arrays):
        """
        Get the cartesian product of a number of arrays.

        Parameters
        ----------
        arrays : Iterable[np.ndarray]
            The arrays to get a cartesian product of. Always sorted with respect
            to the original array.
        Returns
        -------
        out : np.ndarray
            The overall cartesian product of all the input arrays.
        """
        broadcastable = np.ix_(*arrays)
        broadcasted = np.broadcast_arrays(*broadcastable)
        rows, cols = np.prod(broadcasted[0].shape), len(broadcasted)
        dtype = np.result_type(*arrays)
        out = np.empty(rows * cols, dtype=dtype)
        start, end = 0, rows
        for a in broadcasted:
            out[start:end] = a.reshape(-1)
            start, end = end, end + rows
        return out.reshape(cols, rows)