拆分字符串而不丢失字符

I wish to split strings at a certain character while retaining that character in the second resulting string. I can achieve almost all of the desired operation, except that I lose the characters I specify in strsplit, which I guess is called the delimiter.

我希望将字符串拆分为某个字符,同时将该字符保留在第二个结果字符串中。我可以实现几乎所有所需的操作,除了我丢失了我在strsplit中指定的字符,我猜这个字符称为分隔符。

Is there a way to request that strsplit retain the delimiter? Or must I use a regular expression of some kind? Thank you for any advice. This seems like a very basic question. Sorry if it is a duplicate. I prefer to use base R.

有没有办法要求strsplit保留分隔符?或者我必须使用某种正则表达式吗?谢谢你的任何建议。这似乎是一个非常基本的问题。对不起,如果它是重复的。我更喜欢使用底座R.

Here is an example showing what I have so far:

这是一个显示我到目前为止的例子:

my.table <- read.table(text = '
                                                            model npar     AICc 
 AA(~region+state+county+city)BB(~region+state+county+city)CC(~1)   17 11111.11
         AA(~region+state+county)BB(~region+state+county)CC(~123)   14 22222.22
                        AA(~region+state)BB(~region+state)CC(~33)   13 33333.33
                                  AA(~region)BB(~region)CC(~4321)    6 44444.44
', header = TRUE, stringsAsFactors = FALSE)

desired.result <- read.table(text = '
                                                      model        CC npar     AICc
 AA(~region+state+county+city)BB(~region+state+county+city)    CC(~1)   17 11111.11
           AA(~region+state+county)BB(~region+state+county)  CC(~123)   14 22222.22
                         AA(~region+state)BB(~region+state)   CC(~33)   13 33333.33
                                     AA(~region)BB(~region) CC(~4321)    6 44444.44
', header = TRUE, stringsAsFactors = FALSE)

split.model  <- strsplit(my.table$model, 'CC\\(')

split.models <- matrix(unlist(split.model), ncol=2, byrow=TRUE, dimnames = list(NULL, c("model", "CC")))

desires.result2 <- data.frame(split.models, my.table[,2:ncol(my.table)])
desires.result2

#                                                       model     CC npar     AICc
# 1 AA(~region+state+county+city)BB(~region+state+county+city)    ~1)   17 11111.11
# 2           AA(~region+state+county)BB(~region+state+county)  ~123)   14 22222.22
# 3                         AA(~region+state)BB(~region+state)   ~33)   13 33333.33
# 4                                     AA(~region)BB(~region) ~4321)    6 44444.44

3 个解决方案

#1

The basic idea is to use look-around operations from regular expressions to strsplit to get your desired result. However, it's a bit trickier than that with strsplit and positive lookahead. Read this excellent post from @JoshO'Brien for explanation.

基本思想是使用从正则表达式到strsplit的环视操作来获得所需的结果。然而,它比strsplit和积极前瞻更有点棘手。阅读@ JoshO'Brien的这篇优秀文章,以获得解释。

pattern <- "(?<=\\))(?=CC)"
strsplit(my.table$model, pattern, perl=TRUE)
# [[1]]
# [1] "AA(~region+state+county+city)BB(~region+state+county+city)"
# [2] "CC(~1)"                                                    

# [[2]]
# [1] "AA(~region+state+county)BB(~region+state+county)"
# [2] "CC(~123)"                                        

# [[3]]
# [1] "AA(~region+state)BB(~region+state)" "CC(~33)"                           

# [[4]]
# [1] "AA(~region)BB(~region)" "CC(~4321)"             

Of course, I leave the task of do.call(rbind, ...) and cbind to get the final desired.output to you.

当然,我将do.call(rbind,...)和cbind的任务留给你,以获得最终的desired.output。

#2

Almost right after I posted I thought of using gsub to insert a space and then split on the space. Although, I like Arun's answer better.

几乎在我发布后我想到使用gsub插入一个空格然后拆分空间。虽然,我更喜欢阿伦的答案。

my.table <- read.table(text = '
                                                            model npar     AICc 
 AA(~region+state+county+city)BB(~region+state+county+city)CC(~1)   17 11111.11
         AA(~region+state+county)BB(~region+state+county)CC(~123)   14 22222.22
                        AA(~region+state)BB(~region+state)CC(~33)   13 33333.33
                                  AA(~region)BB(~region)CC(~4321)    6 44444.44
', header = TRUE, stringsAsFactors = FALSE)

my.table$model <- gsub("CC", " CC", my.table$model)

split.model <- strsplit(my.table$model, ' ')

split.models <- matrix(unlist(split.model), ncol=2, byrow=TRUE, dimnames = list(NULL, c("model", "CC")))

desires.result <- data.frame(split.models, my.table[,2:ncol(my.table)])
desires.result

#                                                        model        CC npar     AICc
# 1 AA(~region+state+county+city)BB(~region+state+county+city)    CC(~1)   17 11111.11
# 2           AA(~region+state+county)BB(~region+state+county)  CC(~123)   14 22222.22
# 3                         AA(~region+state)BB(~region+state)   CC(~33)   13 33333.33
# 4                                     AA(~region)BB(~region) CC(~4321)    6 44444.44

#3

... why not just tack the separator back on afterwards? Would seem to save a lot of trouble fiddling with regexes.

...为什么不在之后重新点击分隔符?似乎可以省去摆弄正则表达式的麻烦。

split.model <- lapply(strsplit(my.table$model, 'CC\\('), function(x) {
    x[2] <- paste0("CC(", x[2])
    x
})