匹配并替换文本向量中的多个字符串，而无需在R中循环 [英] Match and replace multiple strings in a vector of text without looping in R

问题描述

我正在尝试在R中应用gsub，以将字符串a中的匹配项替换为字符串b中的相应匹配项.例如:

I am trying to apply gsub in R to replace a match in string a with the corresponding match in string b. For example:

a <- c("don't", "i'm", "he'd")
b <- c("do not", "i am", "he would")
c <- c("i'm going to the party", "he'd go too")
newc <- gsub(a, b, c)

期望的结果是

newc = c("i am going to the party", "he would go too")

这种方法行不通，因为gsub仅接受a和b的长度为1的字符串.由于实数a和b的长度为90，而c的长度> 200,000，因此执行循环以遍历a和b的过程将非常缓慢. R中是否存在矢量化方式来执行此操作?

This approach does not work because gsub only accepts a string of length 1 for a and b. Executing a loop to cycle through a and b will be very slow since the real a and b have a length of 90 and c has a length > 200,000. Is there a vectorized way in R to perform this operation?

推荐答案

1)gsubfn包中的gsubfn gsubfn类似于gsub，只是替换字符串可以是字符串，列表，功能或原型对象.如果它是一个列表，它将用名称等于匹配字符串的列表部分替换每个匹配的字符串.

1) gsubfn gsubfn in the gsubfn package is like gsub except the replacement string can be a character string, list, function or proto object. If its a list it will replace each matched string with the component of the list whose name equals the matched string.

library(gsubfn)
gsubfn("\\S+", setNames(as.list(b), a), c)

给予:

[1] "i am going to the party" "he would go too"    

2)gsub 对于没有软件包的解决方案，请尝试以下循环:

2) gsub For a solution with no packages try this loop:

cc <- c
for(i in seq_along(a)) cc <- gsub(a[i], b[i], cc, fixed = TRUE)

给予:

> cc
[1] "i am going to the party" "he would go too"        

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