r - 带有子组的组的反向引用编号

Question

我有“粉丝”一词，当前面带有代词动词组合时，我想用“狂热”一词替换，如下所示。

gsub(
    "(((s?he( i|')s)|((you|they|we)( a|')re)|(I( a|')m)).{1,20})(\\b[Ff]an)(s?\\b)", 
    '\\1\\2atic\\3', 
    'He\'s the bigest fan I know.', 
    perl = TRUE, ignore.case = TRUE
)

## [1] "He's the bigest He'saticHe's I know."

我知道编号的反向引用是指第一组的内括号。有没有办法让它们只引用外面的三个括号，其中三个组是:(fan 之前的东西)(fan)(s\\b) 伪代码。

我知道我的正则表达式可以替换所有组，因为我知道它是有效的。这只是反向引用部分。

gsub(
    "(((s?he( i|')s)|((you|they|we)( a|')re)|(I( a|')m)).{1,20})(\\b[Ff]an)(s?\\b)", 
    '', 
    'He\'s the bigest fan I know.', 
    perl = TRUE, ignore.case = TRUE
)

## [1] " I know."

期望的输出:

## [1] "He's the bigest fanatic I know."

匹配示例

inputs <- c(
    "He's the bigest fan I know.",
    "I am a huge fan of his.",
    "I know she has lots of fans in his club",
    "I was cold and turned on the fan",
    "An air conditioner is better than 2 fans at cooling."
)


outputs <- c(
    "He's the bigest fanatic I know.",
    "I am a huge fanatic of his.",
    "I know she has lots of fanatics in his club",
    "I was cold and turned on the fan",
    "An air conditioner is better than 2 fans at cooling."
)

Answer 1

我知道您在捕获组数量过多时遇到麻烦。把你不感兴趣的变成non-capturing ，或删除那些明显多余的:

((?:s?he(?: i|')s|(?:you|they|we)(?: a|')re|I(?: a|')m).{1,20})\b(Fan)(s?)\b

请参阅regex demo

请注意，[Ff] 可以变成 F 或 f，因为您使用 ignore.case=TRUE 参数。

R demo :

gsub(
    "((?:s?he(?: i|')s|(?:you|they|we)(?: a|')re|I(?: a|')m).{1,20})\\b(fan)(s?)\\b", 
    '\\1\\2atic\\3', 
    inputs, 
    perl = TRUE, ignore.case = TRUE
)

输出:

[1] "He's the bigest fanatic I know."                     
[2] "I am a huge fanatic of his."                         
[3] "I know she has lots of fans in his club"             
[4] "I was cold and turned on the fan"                    
[5] "An air conditioner is better than 2 fans at cooling."