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August 6, 2012 11:51
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python の itertools で遊ぶ
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import itertools | |
# このへん参考: http://kk6.hateblo.jp/entry/20110521/1305984781 | |
# zip_longest はもっとも長いイテレータに合わせて繰り返す | |
# 終わったイテレータには None が入る | |
# [('a', 1), ('b', 2), ('c', None), ('d', None), ('e', None), ('f', None)] | |
print([(char, n) for char, n in itertools.zip_longest("abcdef", range(1, 3))]) | |
# [(1, 'a'), (2, 'b'), (None, 'c'), (None, 'd'), (None, 'e'), (None, 'f')] | |
print([(char, n) for char, n in itertools.zip_longest(range(1, 3), "abcdef")]) | |
# python -V # => Python 3.2.3 | |
# zip 関数はなかった。 | |
# 3.2.3 では itertools.zip() はなかったけど組み込みのzipでよい | |
if not 'zip' in dir(itertools) or 'izip' in dir(itertools): | |
print("itertools.zip() not found.") | |
# もちろんイテレータを組み合わせたりできる | |
# リストではなくジェネレータを返すので速度とかの心配は特にない(と思う) | |
# a 1 | |
# b 2 | |
# c 1 | |
# d 2 | |
# e 1 | |
# f 2 | |
# この例だと zip_longest() では "abcdef" が終了してもループが終わらず無限に繰り返してしまう | |
for x, y in zip("abcdef", itertools.cycle(range(1,3))): | |
print(x, y) |
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