ジェネレータ式を使ったサンプルをいくつかメモ

generator_test.py

# -*- coding:utf-8 -*-

# 総当りジェネレータ
round_robin = lambda L: ((i, j) for i in L for j in L if not i is j)

# タプル -> 辞書リスト
tpl2dcts = lambda L: (dict(zip(L[0], x)) for x in L[1:])

# 2要素ずつ取り出したタプルのジェネレータ
pairs = lambda L: ((L[x], L[x+1]) for x in xrange(0, len(L), 2))

import unittest
class GeneratorTest(unittest.TestCase):
    def test_round_robin(self):
        L = list(round_robin([1, 2, 3, 4]))
        self.assertEqual(L, [
            (1, 2), (1, 3), (1, 4),
            (2, 1), (2, 3), (2, 4),
            (3, 1), (3, 2), (3, 4),
            (4, 1), (4, 2), (4, 3),
        ])

    def test_tpl2dcts(self):
        datas = (
            ("foo", "bar", "baz"),
            (1, 2, 3),
            (4, 5, 6),
            (7, 8, 9),
        )
        L = list(tpl2dcts(datas))
        self.assertEqual(L, [
            dict(foo=1, bar=2, baz=3),
            dict(foo=4, bar=5, baz=6),
            dict(foo=7, bar=8, baz=9),
        ])

    def test_pairs(self):
        L = list(pairs("trebor sux"))
        self.assertEqual(L, [
            ("t", "r"), ("e", "b"), ("o", "r"), (" ", "s"), ("u", "x"),
        ])

if __name__ == "__main__":
    unittest.main()