正则表达式直到括号第一次出现为止

Question

我有一个名为 cars 的字符串，如下所示:

cars
[1] "Only one car(52;model-14557) had a good engine(workable condition), others engine were damaged beyond repair"   
[2] "Other car(21, model-155) looked in good condition but car ( 36, model-8878) looked to be in terrible condition."

我需要从字符串中提取以下部分:

car(52;model-14557)
car(21, model-155)
car ( 36, model-8878)

我尝试使用以下部分来提取它:

stringr::str_extract_all(cars, "(.car\\s{0,5}\\(([^]]+)\\))")

这给了我以下输出:

[[1]]
[1] " car(52;model-14557) had a good engine(workable condition)"

[[2]]
[1] " car(21, model-155) looked in good condition but car ( 36, model-8878)"

有没有办法可以提取汽车一词以及相关的编号和型号？

Answer 1

Your regex does not work因为您使用的是 [^]]+，除 ] 之外的一个或多个与 ( 和 ) 匹配的符号，因此从第一个 ( 到最后一个 ) 匹配，中间没有 ]。

使用

> cars <- c("Only one car(52;model-14557) had a good engine(workable condition), others engine were damaged beyond repair","Other car(21, model-155) looked in good condition but car ( 36, model-8878) looked to be in terrible condition.")
> library(stringr)
> str_extract_all(cars, "\\bcar\\s*\\([^()]+\\)")
[[1]]
[1] "car(52;model-14557)"

[[2]]
[1] "car(21, model-155)"    "car ( 36, model-8878)"

正则表达式为\bcar\s*\([^()]+\)，请参阅online regex demo here .

匹配:

• \b - 单词边界
• car - 文字字符序列
• \s* - 0+ 个空格
• \( - 文字 (
• [^()]+ - 除 ( 和 )之外的 1 个或多个字符
• \) - 文字 )。

请注意，使用以下基本 R 代码，相同的正则表达式将产生相同的结果:

> regmatches(cars, gregexpr("\\bcar\\s*\\([^()]+\\)", cars))
[[1]]
[1] "car(52;model-14557)"

[[2]]
[1] "car(21, model-155)"    "car ( 36, model-8878)"