R 具有正向后看捕获组的gsub正则表达式

我有如下字符串：

 "d1 x2 d2x4 5 specimens collected the smallest is 4 x 1 x 3 mm" 
 " stomach x3 d2x4 8 pieces with the largest measuring  4 x 1 x 3 mm"

我想在“样本”一词前面的数字前加上一个句号，以便

"d1 x2 d2x4 .5 specimens collected the smallest is 4 x 1 x 3 mm" 
" stomach x3 d2x4 .8 pieces with the largest measuring  4 x 1 x 3 mm"

我试过：

regstring<-"specimens|pieces"

gsub(paste0("(","(?<=\\d) ",regString,")"),"\\.\\1",inputString,perl=T)

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如何在数字之前而不是之后获得句号？

您可以使用以下表达式：

(\d+)(\s+(?:specimens|pieces)\b)

并将其替换为

".\\1\\2"

看

---

在

R

中，这可能是

strings <- c("d1 x2 d2x4 5 specimens collected the smallest is 4 x 1 x 3 mm",
            " stomach x3 d2x4 8 pieces with the largest measuring  4 x 1 x 3 mm")
            
strings <- gsub("(\\d+)(\\s+(?:specimens|pieces)\\b)", ".\\1\\2", strings, perl = TRUE)
strings

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strings我想我已经捕捉到了与下面的答案相似的信息：
sub（sprintf（'\\b（\\d+\\s（%s））\\b'，regstring），'.\\1'，inputString）
。我把它复杂化了。感谢您在开始时甚至不需要
\b
。要将样本作为一个整体进行匹配，最好将
\b
移到末尾，即
（\d+）（\s+（？：样本|件）\b）
strings <- c("d1 x2 d2x4 5 specimens collected the smallest is 4 x 1 x 3 mm",
            " stomach x3 d2x4 8 pieces with the largest measuring  4 x 1 x 3 mm")
            
strings <- gsub("(\\d+)(\\s+(?:specimens|pieces)\\b)", ".\\1\\2", strings, perl = TRUE)
strings