batching.py

#   Copyright (c) 2019 PaddlePaddle 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.
"""Mask, padding and batching."""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

import numpy as np


def prepare_batch_data(insts,
                       total_token_num,
                       voc_size=0,
                       pad_id=None,
                       cls_id=None,
                       sep_id=None,
                       mask_id=None,
                       return_input_mask=True,
                       return_max_len=True,
                       return_num_token=False):

    batch_src_ids = [inst[0] for inst in insts]
    batch_sent_ids = [inst[1] for inst in insts]
    batch_pos_ids = [inst[2] for inst in insts]
    batch_mask_pos = [inst[2] for inst in insts]# 这个不需要padding

    # Second step: padding
    src_id, self_input_mask = pad_batch_data(
        batch_src_ids, pad_idx=pad_id, return_input_mask=True)
    pos_id = pad_batch_data(batch_pos_ids, pad_idx=pad_id)
    sent_id = pad_batch_data(batch_sent_ids, pad_idx=pad_id)

    return_list = [
        src_id, pos_id, sent_id, self_input_mask, batch_mask_pos
    ]

    return return_list


def pad_batch_data(insts,
                   pad_idx=0,
                   return_pos=False,
                   return_input_mask=False,
                   return_max_len=False,
                   return_num_token=False,
                   return_seq_lens=False):
    """
    Pad the instances to the max sequence length in batch, and generate the
    corresponding position data and attention bias.
    """
    return_list = []
    max_len = max(len(inst) for inst in insts)
    # Any token included in dict can be used to pad, since the paddings' loss
    # will be masked out by weights and make no effect on parameter gradients.

    inst_data = np.array(
        [inst + list([pad_idx] * (max_len - len(inst))) for inst in insts])
    return_list += [inst_data.astype("int64").reshape([-1, max_len, 1])]

    # position data
    if return_pos:
        inst_pos = np.array([
            list(range(0, len(inst))) + [pad_idx] * (max_len - len(inst))
            for inst in insts
        ])

        return_list += [inst_pos.astype("int64").reshape([-1, max_len, 1])]

    if return_input_mask:
        # This is used to avoid attention on paddings.
        input_mask_data = np.array([[1] * len(inst) + [0] *
                                    (max_len - len(inst)) for inst in insts])
        input_mask_data = np.expand_dims(input_mask_data, axis=-1)
        return_list += [input_mask_data.astype("float32")]

    if return_max_len:
        return_list += [max_len]

    if return_num_token:
        num_token = 0
        for inst in insts:
            num_token += len(inst)
        return_list += [num_token]

    if return_seq_lens:
        seq_lens = np.array([len(inst) for inst in insts])
        return_list += [seq_lens.astype("int64").reshape([-1])]

    return return_list if len(return_list) > 1 else return_list[0]


if __name__ == "__main__":

    pass