Class LegacySeq2SeqDataset

seq2seq/utils.py:204–247

class LegacySeq2SeqDataset(AbstractSeq2SeqDataset):
    def __getitem__(self, index) -> Dict[str, torch.Tensor]:
        """Call tokenizer on src and tgt_lines"""
        index = index + 1  # linecache starts at 1
        source_line = self.prefix + linecache.getline(str(self.src_file), index).rstrip("\n")
        tgt_line = linecache.getline(str(self.tgt_file), index).rstrip("\n")
        assert source_line, f"empty source line for index {index}"
        assert tgt_line, f"empty tgt line for index {index}"
        source_inputs = self.encode_line(self.tokenizer, source_line, self.max_source_length)
        target_inputs = self.encode_line(self.tokenizer, tgt_line, self.max_target_length)

        source_ids = source_inputs["input_ids"].squeeze()
        target_ids = target_inputs["input_ids"].squeeze()
        src_mask = source_inputs["attention_mask"].squeeze()
        return {
            "input_ids": source_ids,
            "attention_mask": src_mask,
            "labels": target_ids,
        }

    def encode_line(self, tokenizer, line, max_length, pad_to_max_length=True, return_tensors="pt"):
        """Only used by LegacyDataset"""
        return tokenizer(
            [line],
            max_length=max_length,
            padding="max_length" if pad_to_max_length else None,
            truncation=True,
            return_tensors=return_tensors,
            **self.dataset_kwargs,
        )

    def collate_fn(self, batch) -> Dict[str, torch.Tensor]:
        input_ids = torch.stack([x["input_ids"] for x in batch])
        masks = torch.stack([x["attention_mask"] for x in batch])
        target_ids = torch.stack([x["labels"] for x in batch])
        pad_token_id = self.pad_token_id
        y = trim_batch(target_ids, pad_token_id)
        source_ids, source_mask = trim_batch(input_ids, pad_token_id, attention_mask=masks)
        batch = {
            "input_ids": source_ids,
            "attention_mask": source_mask,
            "labels": y,
        }
        return batch


class Seq2SeqDataset(AbstractSeq2SeqDataset):