如何将没有重复的整数向量转换为多个连续和离散的部分，并使用 R 以特定格式导出？

Question

Below is a sample data:

dat<-c(1:10,14,17:20,30)

My desired output format is:

1-10,14,17-10,30

I have a large similar vector, that's why I try to use R to make it. Can anyone give some hints\\suggestions? Thank you very much!

Answer 1

You can use diff to create groups of consecutive values and use it in tapply where you can paste first and last value of each group if the length of the values is greater than 1.

dat <- c(1:10,14,17:20,30)

result <- as.character(tapply(dat, cumsum(c(TRUE, diff(dat) > 1)), function(x) {
  if(length(x) == 1) x else paste(x[1], x[length(x)], sep = '-')
}))

result
#[1] "1-10"  "14"    "17-20" "30"   

If you want output as one string.

toString(result)
#[1] "1-10, 14, 17-20, 30"

Answer 2

Base R solution (very similar in principle to Ronak's:

sapply(split(dat, cumsum(c(FALSE, diff(dat) > 1))), function(x){
    paste(unique(range(x)), collapse = "-")
  }
)