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_concat.py
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_concat.py
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# Copyright 2019 The FastEstimator Authors. All Rights Reserved.
#
# Licensed 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.
# ==============================================================================
from typing import List, Optional, TypeVar
import numpy as np
import tensorflow as tf
import torch
Tensor = TypeVar('Tensor', tf.Tensor, torch.Tensor, np.ndarray)
def concat(tensors: List[Tensor], axis: int = 0) -> Optional[Tensor]:
"""Concatenate a list of `tensors` along a given `axis`.
This method can be used with Numpy data:
```python
n = [np.array([[0, 1]]), np.array([[2, 3]]), np.array([[4, 5]])]
b = fe.backend.concat(n, axis=0) # [[0, 1], [2, 3], [4, 5]]
b = fe.backend.concat(n, axis=1) # [[0, 1, 2, 3, 4, 5]]
```
This method can be used with TensorFlow tensors:
```python
t = [tf.constant([[0, 1]]), tf.constant([[2, 3]]), tf.constant([[4, 5]])]
b = fe.backend.concat(t, axis=0) # [[0, 1], [2, 3], [4, 5]]
b = fe.backend.concat(t, axis=1) # [[0, 1, 2, 3, 4, 5]]
```
This method can be used with PyTorch tensors:
```python
p = [torch.tensor([[0, 1]]), torch.tensor([[2, 3]]), torch.tensor([[4, 5]])]
b = fe.backend.concat(p, axis=0) # [[0, 1], [2, 3], [4, 5]]
b = fe.backend.concat(p, axis=1) # [[0, 1, 2, 3, 4, 5]]
```
Args:
tensors: A list of tensors to be concatenated.
axis: The axis along which to concatenate the input.
Returns:
A concatenated representation of the `tensors`, or None if the list of `tensors` was empty.
Raises:
ValueError: If `tensors` is an unacceptable data type.
"""
if len(tensors) == 0:
return None
if tf.is_tensor(tensors[0]):
return tf.concat(tensors, axis=axis)
elif isinstance(tensors[0], torch.Tensor):
return torch.cat(tensors, dim=axis)
elif isinstance(tensors[0], np.ndarray):
return np.concatenate(tensors, axis=axis)
else:
raise ValueError("Unrecognized tensor type {}".format(type(tensors[0])))