用操纵模式替换多个模式

Question

我有一个文本字符串，我想从中转换

text = "end back@drive@o correct back@drive@adjust@cats@do to tok"

到

"end back@drive drive@o correct back@drive drive@adjust adjust@cats cats@do to tok"

相反，一般来说，我想替换

"a@b@c" with "a@b b@c"
"a@b@c@d" with "a@b b@c c@d"

等等。我下面的尝试使用 stringr 包。

patterns = unlist(str_extract_all(text, "([[:alnum:]]+@){2,}[[:alnum:]]+"))
replacements = strsplit(patterns, "@")
replacements = lapply(replacements, function(y) {
  pretuples = y[-length(y)]  
  posttuples = y[-1]
  paste(paste0(pretuples, "@", posttuples), collapse = " ")
})  
replacements = do.call(c, replacements)
str_replace_all(text, pattern = patterns, replacement = replacements)

我不认为str_replace_all是我最后要找的功能，当然它（合理）returns

[1] "end back@drive drive@o correct back@drive@adjust to tok" 
[2] "end back@drive@o correct back@drive drive@adjust adjust@cats cats@do to tok"

谁能帮我解决这个问题？

非常感谢。

编辑：到目前为止的回复非常有用，但我正在解析的文件很大，我真的不知道这个 a@b@c@d... 模式将被链接多少次。是否有更通用的解决方案不依赖于模式长度的硬编码（正如我在上面尝试过的那样）？

Answer 1

> gsub(x = text, pattern = '@(.*?)@', replacement = '@\1 \1@')
[1] "end back@drive drive@o correct back@drive drive@adjust to tok"

您需要提供更多关于您预计会遇到的情况的示例，但解决方案将与上述方向相同。

回应评论 - 您可能需要运行一系列 gsub(x = text, pattern = '@([[:alnum:]]{1,})@', replacement = '@\1 \1@') 在你的文字上，直到它不改变。同样，如果没有更多的测试用例，就无法确定。

Answer 2

我会用 gsub :

> text = "end back@drive@o correct back@drive@adjust to tok"
> gsub(pattern = "([[:alpha:]]+)@([[:alpha:]]+)@([[:alpha:]]+)", replacement = "\1@\2 \2@\3", x = text)
[1] "end back@drive drive@o correct back@drive drive@adjust to tok"

Answer 3

尝试

pat <- "(\s|\b)[^@]+\s(*SKIP)(*FAIL)|(?<=@)([^@]*)(?=@)"
repl <- "\2 \2"
gsub(pat, repl, text, perl=TRUE)
#[1] "end back@drive drive@o correct back@drive drive@adjust adjust@cats cats@do to tok"

对于'str1'

gsub(pat, repl, str1, perl=TRUE)
#[1] "a@b b@c"                     "a@b b@c c@d"                
#[3] "a@b b@c c@d d@e e@f f@g g@h"

数据

text  <- "end back@drive@o correct back@drive@adjust@cats@do to tok"
str1 <- c("a@b@c", "a@b@c@d", "a@b@c@d@e@f@g@h")

用操纵模式替换多个模式

Replacing multiple patterns with manipulated pattern

regex

r

stringr

数据