Frequencies map with Python

frequencies_map.py

from itertools import groupby
from collections import Counter


def frequencies_map_with_for_from(elements):
    frequencies_map = {}
    for element in elements:
        if element in frequencies_map.keys():
            frequencies_map[element] = frequencies_map[element] + 1
        else:
            frequencies_map[element] = 1
    return frequencies_map


def frequencies_map_with_map_and_groupby_from(elements):
    return dict(map(lambda t: (t[0], len(list(t[1]))), groupby(sorted(elements))))


def frequencies_map_with_comprehension_and_groupby_from(elements):
    return {k: len(list(v)) for k, v in groupby(sorted(elements))}


def frequencies_map_with_counter_from(elements):
    return Counter(elements)



def frequencies_map_with_comprehension_and_groupby_from(elements):
    return {k: len(list(v)) for k, v in groupby(sorted(elements))}


def frequencies_map_with_counter_from(elements):
    return Counter(elements)

frequencies_map_test.py

# You will need to have pytest install (globally or in a virtual env)
from frequencies_map import frequencies_map_with_for_from, frequencies_map_with_map_and_groupby_from, frequencies_map_with_comprehension_and_groupby_from, frequencies_map_with_counter_from


class TestFrequenciesMapWithFor:
    def test_empty_list(self):
        assert frequencies_map_with_for_from([]) == {}

    def test_single_element_list(self):
        assert frequencies_map_with_for_from(["a"]) == {"a": 1}

    def test_several_identical_elements_list(self):
        assert frequencies_map_with_for_from(["a", "a", "a"]) == {"a": 3}

    def test_several_different_elements_list_sorted(self):
        assert frequencies_map_with_for_from(["a", "a", "a", "b", "b", "c", "d", "d", "d", "d"]) == {"a": 3, "b": 2, "c": 1, "d": 4}

    def test_several_different_elements_list_unsorted(self):
        assert frequencies_map_with_for_from(["a", "b", "c", "a", "d", "a", "d", "b", "d", "d"]) == {"a": 3, "b": 2, "c": 1, "d": 4}


class TestFrequenciesMapWithMapAndGroupBy:
    def test_empty_list(self):
        assert frequencies_map_with_map_and_groupby_from([]) == {}

    def test_single_element_list(self):
        assert frequencies_map_with_map_and_groupby_from(["a"]) == {"a": 1}

    def test_several_identical_elements_list(self):
        assert frequencies_map_with_map_and_groupby_from(["a", "a", "a"]) == {"a": 3}

    def test_several_different_elements_list_sorted(self):
        assert frequencies_map_with_map_and_groupby_from(["a", "a", "a", "b", "b", "c", "d", "d", "d", "d"]) == {"a": 3, "b": 2, "c": 1, "d": 4}

    def test_several_different_elements_list_unsorted(self):
        assert frequencies_map_with_map_and_groupby_from(["a", "b", "c", "a", "d", "a", "d", "b", "d", "d"]) == {"a": 3, "b": 2, "c": 1, "d": 4}


class TestFrequenciesMapWithComprehensionAndGroupBy:
    def test_empty_list(self):
        assert frequencies_map_with_comprehension_and_groupby_from([]) == {}

    def test_single_element_list(self):
        assert frequencies_map_with_comprehension_and_groupby_from(["a"]) == {"a": 1}

    def test_several_identical_elements_list(self):
        assert frequencies_map_with_comprehension_and_groupby_from(["a", "a", "a"]) == {"a": 3}

    def test_several_different_elements_list_sorted(self):
        assert frequencies_map_with_comprehension_and_groupby_from(["a", "a", "a", "b", "b", "c", "d", "d", "d", "d"]) == {"a": 3, "b": 2, "c": 1, "d": 4}

    def test_several_different_elements_list_unsorted(self):
        assert frequencies_map_with_comprehension_and_groupby_from(["a", "b", "c", "a", "d", "a", "d", "b", "d", "d"]) == {"a": 3, "b": 2, "c": 1, "d": 4}


class TestFrequenciesMapWithCounter:
    def test_empty_list(self):
        assert frequencies_map_with_counter_from([]) == {}

    def test_single_element_list(self):
        assert frequencies_map_with_counter_from(["a"]) == {"a": 1}

    def test_several_identical_elements_list(self):
        assert frequencies_map_with_counter_from(["a", "a", "a"]) == {"a": 3}

    def test_several_different_elements_list_sorted(self):
        assert frequencies_map_with_counter_from(["a", "a", "a", "b", "b", "c", "d", "d", "d", "d"]) == {"a": 3, "b": 2, "c": 1, "d": 4}

    def test_several_different_elements_list_unsorted(self):
        assert frequencies_map_with_counter_from(["a", "b", "c", "a", "d", "a", "d", "b", "d", "d"]) == {"a": 3, "b": 2, "c": 1, "d": 4}