Source code for petastorm.selectors
# Copyright (c) 2017-2018 Uber Technologies, Inc.
#
# 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.
import abc
import six
[docs]@six.add_metaclass(abc.ABCMeta)
class RowGroupSelectorBase(object):
""" Base class for row group selectors."""
[docs] @abc.abstractmethod
def get_index_names(self):
""" Return list of indexes required for given selector."""
[docs] @abc.abstractmethod
def select_row_groups(self, index_dict):
""" Return set of row groups which are selected."""
[docs]class SingleIndexSelector(RowGroupSelectorBase):
"""
Generic selector for single field indexer.
Select all row groups containing any of given values.
"""
def __init__(self, index_name, values_list):
self._index_name = index_name
self._values_to_select = values_list
[docs] def get_index_names(self):
return [self._index_name]
[docs] def select_row_groups(self, index_dict):
indexer = index_dict[self._index_name]
row_groups = set()
for value in self._values_to_select:
row_groups |= indexer.get_row_group_indexes(value)
return row_groups
[docs]class IntersectIndexSelector(RowGroupSelectorBase):
"""
Multiple single-field indexers selector.
Select row groups containing any of the values in all given selectors.
"""
def __init__(self, single_index_selectors):
"""
:param single_index_selectors: List of SingleIndexSelector
"""
self._single_index_selectors = single_index_selectors
[docs] def get_index_names(self):
index_names = []
for single_index_selector in self._single_index_selectors:
index_names.append(single_index_selector.get_index_names()[0])
return index_names
[docs] def select_row_groups(self, index_dict):
row_groups = self._single_index_selectors[0].select_row_groups(index_dict)
for single_index_selector in self._single_index_selectors:
row_groups &= single_index_selector.select_row_groups(index_dict)
return row_groups
[docs]class UnionIndexSelector(RowGroupSelectorBase):
"""
Multiple single-field indexers selector.
Select row groups containing any of the values in at least one selector.
"""
def __init__(self, single_index_selectors):
"""
:param single_index_selectors: List of SingleIndexSelector
"""
self._single_index_selectors = single_index_selectors
[docs] def get_index_names(self):
index_names = []
for single_index_selector in self._single_index_selectors:
index_names.append(single_index_selector.get_index_names()[0])
return index_names
[docs] def select_row_groups(self, index_dict):
row_groups = set()
for single_index_selector in self._single_index_selectors:
row_groups |= single_index_selector.select_row_groups(index_dict)
return row_groups