从字符串中提取数字和名称 [r] [英] Extracting Number and Name from String [r]

问题描述

POSIX 表达式让我头疼.

POSIX Expression is giving me a headache.

假设我们有一个字符串:

Lets say we have a string:

a = "[question(37), question_pipe(\"Person10\")]"

最终我希望能够:

b = c("37", "Person10")

我查看了 stringr 包，但不知道如何使用正则表达式和 str_split 提取信息.

I've had a look at the stringr package but cant figure out how to extract the information out using regular expressions and str_split.

任何帮助将不胜感激.

卡梅隆

推荐答案

所以如果我理解正确的话，你想提取括号内的元素.

So if I understand correctly you want to extract the elements within parenthesis.

您可以首先使用 str_extract_all 提取这些元素，包括括号:

You can first extract those elements, including the parenthesis, using str_extract_all:

b1 <- str_extract_all(string = a, pattern = "\\(.*?\\)")
b1
# [[1]]
# [1] "(37)"           "(\"Person10\")"

既然 str_extract_all 返回一个列表，我们把它变成一个向量:

Since str_extract_all returns a list, let's turn it into a vector:

b2 <- unlist(b1)
b2
# [1] "(37)"           "(\"Person10\")"

最后，您可以使用str_sub去除括号(每个字符串的第一个和最后一个字符):

Last, you can remove the parenthesis (the first and last character of each string) using str_sub:

b3 <- str_sub(string = b2, start = 2L, end = -2L) 
b3
# [1] "37"           "\"Person10\""

关于正则表达式模式的一些评论:\\( 和 \\) 是您的左括号和右括号..*? 表示任何字符串但不贪婪，否则你会得到一个从第一个 ( 到最后一个 ) 的长匹配.

A few comments about the regex pattern: \\( and \\) are your opening and closing parenthesis. .*? means any character string but without being greedy, otherwise you would get one long match from the first ( to the last ).

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