r 中 sapply 和 lapply 的语法 [英] Syntax of sapply and lapply in r

问题描述

我一直在寻找根据子值的索引在 r 中分隔列表的方法，我看到这段代码弹出了很多:

I have been looking into ways to separate a list in r based on the index of the sub values and I have seen this piece of code pop up a lot:

sapply(myList, "[", 2)

我想知道是否有人能够向我解释这一点，因为我之前用于 sapply 的唯一语法是:

I was wondering if anyone would be able to explain this to me as the only syntax that I have used for sapply before is:

sapply(myList, Function)

推荐答案

"[" 本身就是一个函数.

当您调用 sapply(LIST, "[", 2) 时，表示提取每个子列表的第二个元素.

when you call sapply(LIST, "[", 2) it means extract the second element of each sub-list.

您传递的 2 作为函数 [ 的参数，使其成为 [2]

The 2 which you passed goes as an argument to the function [ making it [2]

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