gsub 替换中的函数 [英] Function in gsub replacement

问题描述

是否可以在 gsub 替换短语中应用函数?假设在 str_to_title 之后我们有

Is it possible to apply function in gsub replacement phrase ? Let's say after str_to_title we have

这是一个地狱般的Blahblah蛋糕

我想从 str_to_title 函数的效果中忽略某些词，这样我就有

I would like ignore certain words from the effect of str_to_title function, so that I would have

This is one Hell of a blahblah Cake

我知道 str_to_title 有自己的异常列表，但我想通过将某些短语恢复为小写来自定义该列表.

I am aware that str_to_title has its own list of exception, but I would like to customize that list by reverting some phrase back to lowercase.

我目前的做法是

gsub("( Is | One | BlahBlah )", tolower("\\1"), str_to_title(x))

但是 gsub 不会看到 tolower 函数.一个想法如何实现这一目标?我们如何用作用于匹配字符串的函数替换正则表达式?

but gsub will not see the tolower function. An idea how t achieve this ? How can we replace regex with a function acting on the matched string ?

推荐答案

您可以使用 \\L 将它们转换为小写:

You can prefix the replacement with \\L to convert them to lower case:

s = "This Is One Hell Of A Blahblah Cake"

gsub("(\\bIs\\b|\\bOne\\b|\\bBlahblah\\b)", "\\L\\1", s, perl = T)
# [1] "This is one Hell Of A blahblah Cake"

或者如@joran 所评论的，您可以使用 gsubfn 包:

Or as commented @joran, you can use gsubfn package:

library(gsubfn)
options(gsubfn.engine = "R")
gsubfn("\\bIs\\b|\\bOne\\b|\\bBlahblah\\b", ~ tolower(x), s)
# [1] "This is one Hell Of A blahblah Cake"

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