[GitHub] [incubator-mxnet] hgt312 commented on a change in pull request #16564: [numpy] add numpy operator : append

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hgt312 commented on a change in pull request #16564: [numpy] add numpy operator : append
URL: https://github.com/apache/incubator-mxnet/pull/16564#discussion_r337877040
 
 

 ##########
 File path: python/mxnet/numpy/multiarray.py
 ##########
 @@ -6419,3 +6419,47 @@ def einsum(*operands, **kwargs):
     ...     np.einsum('ijk,ilm,njm,nlk,abc->',a,a,a,a,a, optimize=True)
     """
     return _mx_nd_np.einsum(*operands, **kwargs)
+
+
+@set_module('mxnet.numpy')
+def append(arr, values, axis=None):
+    """
+    Append values to the end of an array.
+    Parameters
+    ----------
+    arr : ndarray
+        Values are appended to a copy of this array.
+    values : ndarray
+        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
+    -------
+    append : 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(np.array([1, 2, 3]), np.array([[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(np.array([[1, 2, 3], [4, 5, 6]]), np.array([[7, 8, 9]]), axis=0)
+    array([[1., 2., 3.],
+           [4., 5., 6.],
+           [7., 8., 9.]])
+    """
+    if axis is None:
+        arr = arr.flatten()
+        values = values.flatten()
+        axis = 0
+    return concatenate((arr, values), axis=axis)
 
 Review comment:
   Do not return `concat` here, it makes the function in `_op` unused
   ```suggestion
       return _mx_nd_np.append(...)
   ```
   Besides, argument `axis` in `append` and `concat` has the same effect, just pass the ndarrays is OK, no need to flatten.

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