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Slicing input tensor by its positions
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import tensorflow as tf | |
import numpy as np | |
input_data = np.random.rand(10, 10, 64) | |
positions = [0,9,8,2,3,5,1,2,4,6] | |
input_tensor = tf.placeholder(shape = (None,10,64) , dtype = tf.float32) | |
positions_tensor = tf.placeholder(shape = (None,) , dtype = tf.int32) | |
def gather_indexes(input_tensor, positions): | |
"""Gathers the vectors at the specific positions over a minibatch.""" | |
batch_size = tf.shape(input_tensor)[0] | |
seq_length = tf.shape(input_tensor)[1] | |
dim = tf.shape(input_tensor)[2] | |
flat_offsets = tf.reshape(tf.range(0, batch_size, dtype=tf.int32) * seq_length, [-1, 1]) | |
flat_positions = tf.reshape(tf.expand_dims(positions, axis=-1) + flat_offsets, [-1]) | |
flat_sequence_tensor = tf.reshape(input_tensor, | |
[batch_size * seq_length, dim]) | |
output_tensor = tf.gather(flat_sequence_tensor, flat_positions) ## slices tensor by positions | |
return output_tensor | |
init = tf.global_variables_initializer() | |
with tf.Session() as sess: | |
sess.run(init) | |
result = sess.run(gather_indexes(input_tensor, positions_tensor), | |
feed_dict = {input_tensor: input_data, | |
positions_tensor: positions}) | |
## check result | |
print(result[0]) | |
print(input_data[0][positions[0]]) |
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