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# Licensed under the Apache License, Version 2.0 (the "License");
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# http://www.apache.org/licenses/LICENSE-2.0
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[docs]def sequence_mask(seq_ids, valid_lengths):
"""
To boost the performance, this sequence_mask is different with paddle.fluid.layers.sequence_mask
Args:
seq_ids (Tensor): The whole sequence index, a tensor with shape `[batch_size, sequence_length]`.
valid_lengths (Tensor): The valid length of every sequence, a tensor with shape `[batch_size]`
Returns:
Tensor: The output sequence mask.
"""
lengths_exp = valid_lengths.unsqueeze(1).expand_as(seq_ids)
mask = seq_ids < lengths_exp
return mask