[英]Using gsub for a specific occurrence in a string in R?
我有两个字符串:
mystring1 <- c("hello i am a cat. just kidding, i'm not a cat i'm a cat. dogs are the best animal. not cats!")
mystring2 <- c("hello i am a cat. just kidding, i'm not a cat i'm a cat. but i have a cat friend that is a cat.")
我想将两个字符串中单词 cat 的第三次出现更改为 dog。
理想情况下, string1
和string2
将读取:
mystring1
[1] "hello i am a cat. just kidding, i'm not a cat i'm a dog. dogs are the best animal. not cats!"
mystring2
[1] "hello i am a cat. just kidding, i'm not a cat i'm a dog. but i have a cat friend that is a cat."
这样做的最佳方法是什么? 到目前为止,我只使用gsub
替换字符,但我不知道这是否可以用来替换特定出现的字符。
你可以使用
mystring1 <- c("hello i am a cat. just kidding, i'm not a cat i'm a cat. dogs are the best animal. not cats!")
mystring2 <- c("hello i am a cat. just kidding, i'm not a cat i'm a cat. but i have a cat friend that is a cat who knows a cat knowing a cat.")
sub("((cat.*?){2})\\bcat\\b", "\\1dog", mystring1, perl=TRUE)
这使
> sub("((cat.*?){2})\\bcat\\b", "\\1dog", c(mystring1, mystring2), perl=TRUE)
[1] "hello i am a cat. just kidding, i'm not a cat i'm a dog. dogs are the best animal. not cats!"
[2] "hello i am a cat. just kidding, i'm not a cat i'm a dog. but i have a cat friend that is a cat who knows a cat knowing a cat."
您可以使用gsubfn
library(gsubfn)
p <- proto(fun = function(this, x) if(count == 3) 'dog' else x)
gsubfn('cat', p, c(mystring1, mystring2))
# [1] "hello i am a cat. just kidding, i'm not a cat i'm a dog. dogs are the best animal. not cats!"
# [2] "hello i am a cat. just kidding, i'm not a cat i'm a dog. but i have a cat friend that is a cat."
或者,如果它需要被单词边界包围,
gsubfn('\\bcat\\b', p, c(mystring1, mystring2), perl = TRUE)
# [1] "hello i am a cat. just kidding, i'm not a cat i'm a dog. dogs are the best animal. not cats!"
# [2] "hello i am a cat. just kidding, i'm not a cat i'm a dog. but i have a cat friend that is a cat."
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.