回答編集履歴
2
追記
answer
CHANGED
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@@ -20,4 +20,50 @@
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x_org = ['a', 'b', 'c', 'd']
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x_list = list(chain.from_iterable(zip(*tee(x_org, 2))))
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```
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----
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追記
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ちなみになんですが、質問に書いてあるコードが最速だと思います。
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```plain
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In [1]: from itertools import chain, repeat, tee
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...:
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...: def a(x_org):
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...: return [x for x in x_org for _i in range(2)]
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...:
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...: def aa(x_org):
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...: return [y for x in ['a', 'b', 'c', 'd'] for y in [x] * 2]
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...:
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...: def b(x_org):
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...: return list(chain.from_iterable([x] * 2 for x in x_org))
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...:
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...: def c(x_org):
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...: return list(chain.from_iterable(zip(*tee(x_org, 2))))
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...:
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...: def d(x_org):
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...: x_list = []
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...: for x in x_org:
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...: x_list.append(x)
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...: x_list.append(x)
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...: return x_list
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...:
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In [2]: x_org = ['a', 'b', 'c', 'd']
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In [3]: %timeit a(x_org)
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1.33 µs ± 44.9 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)
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In [4]: %timeit aa(x_org)
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991 ns ± 29.4 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)
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In [5]: %timeit b(x_org)
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1.25 µs ± 5.31 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)
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In [6]: %timeit c(x_org)
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1.08 µs ± 42.1 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)
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In [7]: %timeit d(x_org)
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617 ns ± 25.7 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)
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```
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1
些細
answer
CHANGED
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@@ -14,7 +14,7 @@
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```
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-
(3)teeとzipで`
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(3)teeとzipで`('a', 'a'), ('b', 'b'),,,` のシーケンスを作ってflatten
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```python
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from itertools import chain, tee
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