AttributeFilter

Complexity

Total Complexity

7

Size/Duplication

Total Lines	26
Duplicated Lines	0 %

Importance

Changes	1
Bugs	0	Features	0

3 Methods

Rating	Name	Duplication	Size	Complexity
A	__init__()	0	4	1
A	excluding()	0	4	3
A	including()	0	4	3

"""
Utilities for filtering sequences.
"""

from itertools import product, chain
from operator import attrgetter, itemgetter
from typing import Dict, Generator, List, Tuple

The import typing could not be resolved.

class AttributeFilter:
    """
    Filter a sequence of objects/namedtuples by on attribute value predicates.

    Parameters
    ----------
    keys: group of attribute keys to use as filter set.
    predicates: values of attribute set to use in filtering.
    """

    slots = ('keys', 'predicates', 'indexer')

    def __init__(self, keys: Tuple[str], predicates: List[Tuple]):
        self.keys = keys
        self.predicates = set(predicates)
        self.indexer = attrgetter(*keys)

Usage of * or ** arguments should usually be done with care.

    def including(self, sequence) -> Generator:
        """Include the sequence elements matching the filter set."""
        return (element for element in sequence
                if self.indexer(element) in self.predicates)

    def excluding(self, sequence) -> Generator:
        """Exclude the sequence elements matching the filter set."""
        return (element for element in sequence
                if self.indexer(element) not in self.predicates)


def create_key_filter(properties: Dict[str, list]) -> List[Tuple]:
    """Generate combinations of key, value pairs for each key in properties.

    Examples
    --------
    properties = {'ent': ['geo_rev', 'supply_chain'], 'own', 'fi'}
    >> create_key_filter(properties)
      --> [('ent', 'geo_rev'), ('ent', 'supply_chain'), ('own', 'fi')]
    """

    combinations = (product([k], v) for k, v in properties.items())

    return chain.from_iterable(combinations)


def create_indexer(indexes: list):
    """Create indexer function to pluck values from list."""

    if len(indexes) == 1:
        index = indexes[0]
        return lambda x: (x[index],)
    else:
        return itemgetter(*indexes)

Usage of * or ** arguments should usually be done with care.