[英]How do I add text to every other item in a python list?
我有一個類似的清單:
mylist = ["1", "2", "3", "4", "5"]
我想向其他所有項目添加一些文本,因此看起來像這樣:
mylist = ["1a", "2", "3a", "4", "5a"]
我寫了這個,對每個項目都很好用。 如何使它僅適用於其他所有項目?
mylist2 = ["a" + item for item in mylist]
一種方法是:
mylist = ["1", "2", "3", "4", "5"]
res = [x + ('a' if i%2 == 0 else '') for i, x in enumerate(mylist)]
結果是:
['1a', '2', '3a', '4', '5a']
這種方法利用了以下事實:要除以2時要更改的術語的索引的余數為1。請參見模
嘗試這個:
for i in range(0, len(mylist), 2):
mylist[i] = mylist[i] + "a"
編輯1:
for i in range(0, len(mylist), 2):
mylist[i] += "a"
使用enumerate
和模以三進制測試奇數或偶數。
mylist = ["1", "2", "3", "4", "5"]
mylist2 = [item if i%2 else "a" + item for i,item in enumerate(mylist)]
結果:
>>> mylist2
['a1', '2', 'a3', '4', 'a5']
得到1a
,依此類推...只需切換"a" + item
item + "a"
有點奇怪的解決方案,它使用了迭代器:
>>> from itertools import cycle
>>> mylist = ["1", "2", "3", "4", "5"]
>>> suffix = cycle(["a", ""])
>>> [l + s for l, s in zip(mylist, suffix)]
['1a', '2', '3a', '4', '5a']
編輯
正如Netwave在評論中所建議的那樣,這是非常超級的Python解決方案!
>>> import itertools, operator
>>> list(map(operator.add, mylist, itertools.cycle(("a", ""))))
['1a', '2', '3a', '4', '5a']
mylist = ["1", "2", "3", "4", "5"] text_list = [str(x) + 'a' if i % 2 == 0 else x for i, x in enumerate(mylist)]
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