查找字符在字符串中的位置 [英] Find the location of a character in string

问题描述

我想找到一个字符在字符串中的位置.

I would like to find the location of a character in a string.

说:string = "the2quickbrownfoxeswere2tired"

我希望函数返回 4 和 24 -- 2 在 string.

I would like the function to return 4 and 24 -- the character location of the 2s in string.

推荐答案

您可以使用 gregexpr

 gregexpr(pattern ='2',"the2quickbrownfoxeswere2tired")


[[1]]
[1]  4 24
attr(,"match.length")
[1] 1 1
attr(,"useBytes")
[1] TRUE

或者 str_locate_all 来自包 stringr，它是 gregexpr stringi::stri_locate_all 的包装器(从 stringr 1.0 版开始)

or perhaps str_locate_all from package stringr which is a wrapper for gregexpr stringi::stri_locate_all (as of stringr version 1.0)

library(stringr)
str_locate_all(pattern ='2', "the2quickbrownfoxeswere2tired")

[[1]]
     start end
[1,]     4   4
[2,]    24  24

请注意，您可以简单地使用 stringi

note that you could simply use stringi

library(stringi)
stri_locate_all(pattern = '2', "the2quickbrownfoxeswere2tired", fixed = TRUE)

基础 R 中的另一个选项类似于

Another option in base R would be something like

lapply(strsplit(x, ''), function(x) which(x == '2'))

应该可以工作(给定一个字符向量 x)

should work (given a character vector x)

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