# Copyright 2019-2021 Huawei Technologies Co., Ltd
#
# 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.
# ==============================================================================
"""
This module is to support reading page from MindRecord.
"""
from .shardsegment import ShardSegment
from .shardutils import check_parameter
from .common.exceptions import ParamValueError, ParamTypeError, MRMDefineCategoryError
__all__ = ['MindPage']
[文档]class MindPage:
"""
Class to read MindRecord files in pagination.
Args:
file_name (Union[str, list[str]]): One of MindRecord files or a file list.
num_consumer (int, optional): The number of reader workers which load data. Default: ``4`` .
It should not be smaller than 1 or larger than the number of processor cores.
Raises:
ParamValueError: If `file_name` , `num_consumer` or columns is invalid.
MRMInitSegmentError: If failed to initialize ShardSegment.
Examples:
>>> from mindspore.mindrecord import MindPage
>>>
>>> mindrecord_file = "/path/to/mindrecord/file"
>>> mind_page = MindPage(mindrecord_file)
>>>
>>> # get all the index fields
>>> fields = mind_page.candidate_fields
>>>
>>> # set the field to be retrieved
>>> mind_page.category_field = "file_name"
>>>
>>> # get all the group info
>>> info = mind_page.read_category_info()
>>>
>>> # get the row by id which is from category info
>>> row_by_id = mind_page.read_at_page_by_id(0, 0, 1)
>>>
>>> # get the row by name which is from category info
>>> row_by_name = mind_page.read_at_page_by_name("8.jpg", 0, 1)
"""
@check_parameter
def __init__(self, file_name, num_consumer=4):
self._segment = ShardSegment()
self._segment.open(file_name, num_consumer)
self._category_field = None
self._candidate_fields = [field[:field.rfind('_')] for field in self._segment.get_category_fields()]
@property
def candidate_fields(self):
"""
Return candidate category fields.
Note:
Please refer to the Examples of :class:`mindspore.mindrecord.MindPage` .
Returns:
list[str], by which data could be grouped.
"""
return self._candidate_fields
@property
def category_field(self):
"""
Getter function for category fields.
Note:
Please refer to the Examples of :class:`mindspore.mindrecord.MindPage` .
Returns:
list[str], by which data could be grouped.
"""
return self._category_field
@category_field.setter
def category_field(self, category_field):
"""
Setter function for category field.
Note:
Please refer to the Examples of :class:`mindspore.mindrecord.MindPage` .
Returns:
MSRStatus, SUCCESS or FAILED.
"""
if not category_field or not isinstance(category_field, str):
raise ParamTypeError('category_fields', 'str')
if category_field not in self._candidate_fields:
raise MRMDefineCategoryError("Field '{}' is not a candidate category field.".format(category_field))
self._category_field = category_field
return self._segment.set_category_field(self._category_field)
[文档] def read_category_info(self):
"""
Return category information when data is grouped by indicated category field.
Note:
Please refer to the Examples of :class:`mindspore.mindrecord.MindPage` .
Returns:
str, description of group information.
Raises:
MRMReadCategoryInfoError: If failed to read category information.
"""
return self._segment.read_category_info()
[文档] def read_at_page_by_id(self, category_id, page, num_row):
"""
Query by category id in pagination.
Note:
Please refer to the Examples of :class:`mindspore.mindrecord.MindPage` .
Args:
category_id (int): Category id, referred to the return of `read_category_info` .
page (int): Index of page.
num_row (int): Number of rows in a page.
Returns:
list[dict], data queried by category id.
Raises:
ParamValueError: If any parameter is invalid.
MRMFetchDataError: If failed to fetch data by category.
MRMUnsupportedSchemaError: If schema is invalid.
"""
if not isinstance(category_id, int) or category_id < 0:
raise ParamValueError("Category id should be int and greater than or equal to 0.")
if not isinstance(page, int) or page < 0:
raise ParamValueError("Page should be int and greater than or equal to 0.")
if not isinstance(num_row, int) or num_row <= 0:
raise ParamValueError("num_row should be int and greater than 0.")
return self._segment.read_at_page_by_id(category_id, page, num_row)
[文档] def read_at_page_by_name(self, category_name, page, num_row):
"""
Query by category name in pagination.
Note:
Please refer to the Examples of :class:`mindspore.mindrecord.MindPage` .
Args:
category_name (str): String of category field's value,
referred to the return of `read_category_info` .
page (int): Index of page.
num_row (int): Number of row in a page.
Returns:
list[dict], data queried by category name.
"""
if not isinstance(category_name, str):
raise ParamValueError("Category name should be str.")
if not isinstance(page, int) or page < 0:
raise ParamValueError("Page should be int and greater than or equal to 0.")
if not isinstance(num_row, int) or num_row <= 0:
raise ParamValueError("num_row should be int and greater than 0.")
return self._segment.read_at_page_by_name(category_name, page, num_row)