list 从列表中选择多个元素
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Select multiple elements from a list
提问by user1357015
I have a list in R some 10,000 elements long. Say I want to select only elements, 5, 7, and 9. I'm not sure how I would do that without a for loop.
我在 R 中有一个大约 10,000 个元素的列表。假设我只想选择元素 5、7 和 9。如果没有 for 循环，我不确定如何做到这一点。
I want to do something like mylist[[c(5,7,9]]but that doesn't work. I've also tried the lapplyfunction but haven't been able to get that working either.
我想做类似的事情，mylist[[c(5,7,9]]但这不起作用。我也尝试过该lapply功能，但也无法使其正常工作。
回答by Glen_b
mylist[c(5,7,9)]should do it.
mylist[c(5,7,9)]应该这样做。
You want the sublists returned as sublists of the result list; you don't use [[]](or rather, the function is [[) for that -- as Dason mentions in comments, [[grabs the element.
您希望子列表作为结果列表的子列表返回；你不使用[[]]（或者更确切地说，函数是[[） - 正如 Dason 在评论中提到的那样，[[抓取元素。
