如何在特定字符串后提取所有内容? [英] How to extract everything after a specific string?

问题描述

我想提取 R 中字符串向量中-"之后的所有内容.

I'd like to extract everything after "-" in vector of strings in R.

例如:

test = c("Pierre-Pomme","Jean-Poire","Michel-Fraise")

我想得到

c("Pomme","Poire","Fraise")

谢谢！

推荐答案

With str_extract.\\b 是匹配字边界的零长度标记.这包括任何非单词字符:

With str_extract. \\b is a zero-length token that matches a word-boundary. This includes any non-word characters:

library(stringr)
str_extract(test, '\\b\\w+$')
# [1] "Pomme"  "Poire"  "Fraise"

我们也可以使用带有 sub 的反向引用.\\1 指的是与第一个捕获组(.+) 匹配的字符串，它是在 - 之后一次或多次的任何字符结束:

We can also use a back reference with sub. \\1 refers to string matched by the first capture group (.+), which is any character one or more times following a - at the end:

sub('.+-(.+)', '\\1', test)
# [1] "Pomme"  "Poire"  "Fraise"

这也适用于 str_replace 如果已经加载:

This also works with str_replace if that is already loaded:

library(stringr)
str_replace(test, '.+-(.+)', '\\1')
# [1] "Pomme"  "Poire"  "Fraise"

第三个选项是使用 strsplit 并从列表的每个元素中提取第二个单词(类似于@akrun 答案中的 word):

Third option would be using strsplit and extract the second word from each element of the list (similar to word from @akrun's answer):

sapply(strsplit(test, '-'), `[`, 2)
# [1] "Pomme"  "Poire"  "Fraise"

stringr 也有这样的 str_split 变体:

stringr also has str_split variant to this:

str_split(test, '-', simplify = TRUE)[,2]
# [1] "Pomme"  "Poire"  "Fraise"

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