【help of python】append函数

>>>help(append)
Help on function append in module numpy.lib.function_base:

append(arr, values, axis=None)
Append values to the end of an array.

Parameters
----------
arr : array_like
    Values are appended to a copy of this array.
values : array_like
    These values are appended to a copy of `arr`.  It must be of the
    correct shape (the same shape as `arr`, excluding `axis`).  If `axis`
    is not specified, `values` can be any shape and will be flattened
    before use.
axis : int, optional
    The axis along which `values` are appended.  If `axis` is not given,
    both `arr` and `values` are flattened before use.

Returns
-------
out : ndarray
    A copy of `arr` with `values` appended to `axis`.  Note that `append`
    does not occur in-place: a new array is allocated and filled.  If
    `axis` is None, `out` is a flattened array.

See Also
--------
insert : Insert elements into an array.
delete : Delete elements from an array.

Examples
--------
>>> np.append([1, 2, 3], [[4, 5, 6], [7, 8, 9]])
array([1, 2, 3, 4, 5, 6, 7, 8, 9])

When `axis` is specified, `values` must have the correct shape.

>>> np.append([[1, 2, 3], [4, 5, 6]], [[7, 8, 9]], axis=0)
array([[1, 2, 3],
       [4, 5, 6],
       [7, 8, 9]])
>>> np.append([[1, 2, 3], [4, 5, 6]], [7, 8, 9], axis=0)
Traceback (most recent call last):
...
ValueError: arrays must have same number of dimensions