shows how to create a multivalue dict from tuples

grouping_edges_map_reduce.py

from typing import Iterable, Tuple, Dict, Set
from more_itertools import map_reduce


def group_edges(edges: Iterable[Tuple[str, str]]) -> Dict[str, Set[str]]:
    return map_reduce(
        edges,
        keyfunc=lambda edge: edge[0],  # 1
        valuefunc=lambda edge: edge[1],  # 2
        reducefunc=set,  # 3
    )


def test_group_edges_by_source_node():
    edges = [
        ("n1", "n2"),
        ("n2", "n3"),
        ("n1", "n3"),
        ("n1", "n2"),
        ("n3", "n4"),
        ("n1", "n4"),
        ("n2", "n4"),
    ]

    actual_grouping = group_edges(edges)

    expected_grouping = {"n1": {"n2", "n3", "n4"}, "n2": {"n3", "n4"}, "n3": {"n4"}}
    assert actual_grouping == expected_grouping