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[英]Selecting specific elements that contain a certain word from a list in python
[英]python check if word is in certain elements of a list
我想知道是否有更好的方法:
if word==wordList[0] or word==wordList[2] or word==wordList[3] or word==worldList[4]
word in wordList
或者,如果你想先检查4,
word in wordList[:4]
非常简单的任务,以及很多方法来处理它。 精彩! 这是我的想法:
如果您确定wordList很小(否则它可能效率太低),那么我建议使用这个:
b = word in (wordList[:1] + wordList[2:])
否则我可能会这样做(仍然,这取决于!):
b = word in (w for i, w in enumerate(wordList) if i != 1)
例如,如果要忽略多个索引:
ignore = frozenset([5, 17])
b = word in (w for i, w in enumerate(wordList) if i not in ignore)
这是pythonic,它可以扩展。
但是,有一些值得注意的替代方案:
### Constructing a tuple ad-hoc. Easy to read/understand, but doesn't scale.
# Note lack of index 1.
b = word in (wordList[0], wordList[2], wordList[3], wordList[4])
### Playing around with iterators. Scales, but rather hard to understand.
from itertools import chain, islice
b = word in chain(islice(wordList, None, 1), islice(wordList, 2, None))
### More efficient, if condition is to be evaluated many times in a loop.
from itertools import chain
words = frozenset(chain(wordList[:1], wordList[2:]))
b = word in words
让indexList成为您要检查的指标列表(即[0,2,3]
),并让wordList成为您要检查的所有单词。 然后,以下命令将返回wordList的第0,第2和第3个元素,作为列表:
[wordList[i] for i in indexList]
这将返回[wordList[0], wordList[2], wordList[3]]
。
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