chore: import upstream snapshot with attribution

python/tvm/topi/testing/sequence_mask_python.py

@@ -0,0 +1,55 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+# pylint: disable=invalid-name
+"""Sequence mask in python"""
+
+import numpy as np
+
+
+def sequence_mask(data, valid_length, mask_value, axis):
+    """batch_matmul operator implemented in numpy.
+
+    Parameters
+    ----------
+    data : numpy.ndarray
+        N-D with shape [batch_size, MAX_LENGTH, ...] or [MAX_LENGTH, batch_size, ...]
+
+    valid_length : numpy.ndarray
+        1-D with shape [batch_size,]
+
+    mask_value : float
+        Masking value
+
+    axis : int
+        The axis of the length dimension
+
+    Returns
+    -------
+    out : numpy.ndarray
+        N-D with shape same as data
+    """
+    in_shape = data.shape
+    max_length = data.shape[axis]
+    val_len_expand_shape = [1 for _ in range(len(in_shape))]
+    val_len_expand_shape[1 - axis] = in_shape[1 - axis]
+    seq_len_expand_shape = [1 for _ in range(len(in_shape))]
+    seq_len_expand_shape[axis] = in_shape[axis]
+    mask = np.broadcast_to(
+        np.arange(max_length).reshape(seq_len_expand_shape), in_shape
+    ) >= valid_length.reshape(val_len_expand_shape)
+    out = data * (1 - mask) + mask_value * mask
+    return out