torch.nn.utils.rnn.unpad_sequence — PyTorch 2.7 documentation (original) (raw)
torch.nn.utils.rnn.unpad_sequence(padded_sequences, lengths, batch_first=False)[source][source]¶
Unpad padded Tensor into a list of variable length Tensors.
unpad_sequence unstacks padded Tensor into a list of variable length Tensors.
Example
from torch.nn.utils.rnn import pad_sequence, unpad_sequence a = torch.ones(25, 300) b = torch.ones(22, 300) c = torch.ones(15, 300) sequences = [a, b, c] padded_sequences = pad_sequence(sequences) lengths = torch.as_tensor([v.size(0) for v in sequences]) unpadded_sequences = unpad_sequence(padded_sequences, lengths) torch.allclose(sequences[0], unpadded_sequences[0]) True torch.allclose(sequences[1], unpadded_sequences[1]) True torch.allclose(sequences[2], unpadded_sequences[2]) True
Parameters
- padded_sequences (Tensor) – padded sequences.
- lengths (Tensor) – length of original (unpadded) sequences.
- batch_first (bool, optional) – whether batch dimension first or not. Default:
False.
Returns
a list of Tensor objects
Return type