forked from huawei/mindspore2022
80 lines
2.9 KiB
Python
80 lines
2.9 KiB
Python
# Copyright 2019-2021 Huawei Technologies Co., Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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# ==============================================================================
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"""
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This module is to read data from MindRecord.
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"""
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from .shardreader import ShardReader
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from .shardheader import ShardHeader
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from .shardutils import populate_data
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from .shardutils import check_parameter
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from .common.exceptions import ParamTypeError
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__all__ = ['FileReader']
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class FileReader:
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"""
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Class to read MindRecord files.
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Note:
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If `file_name` is a filename string, it tries to load all MindRecord files generated \
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in a conversion, and throws an exceptions if a MindRecord file is missing.
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If `file_name` is a filename list, only the MindRecord files in the list are loaded.
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Args:
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file_name (str, list[str]): One of MindRecord file or a file list.
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num_consumer(int, optional): Number of reader workers which load data. Default: 4.
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It should not be smaller than 1 or larger than the number of processor cores.
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columns (list[str], optional): A list of fields where corresponding data would be read. Default: None.
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operator(int, optional): Reserved parameter for operators. Default: None.
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Raises:
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ParamValueError: If `file_name`, `num_consumer` or `columns` is invalid.
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"""
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@check_parameter
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def __init__(self, file_name, num_consumer=4, columns=None, operator=None):
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if columns:
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if isinstance(columns, list):
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self._columns = columns
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else:
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raise ParamTypeError('columns', 'list')
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else:
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self._columns = None
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self._reader = ShardReader()
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self._reader.open(file_name, num_consumer, columns, operator)
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self._header = ShardHeader(self._reader.get_header())
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self._reader.launch()
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def get_next(self):
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"""
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Yield a batch of data according to columns at a time.
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Yields:
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Dict: a batch whose keys are the same as columns.
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Raises:
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MRMUnsupportedSchemaError: If schema is invalid.
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"""
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iterator = self._reader.get_next()
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while iterator:
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for blob, raw in iterator:
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yield populate_data(raw, blob, self._columns, self._header.blob_fields, self._header.schema)
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iterator = self._reader.get_next()
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def close(self):
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"""Stop reader worker and close File."""
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self._reader.close()
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