How do I insert "-" after the 4th number of 0912345678-CodePudding

How do I insert "-" between the fourth and fifth numbers of 0912345678 like 0912-345678

I have tried the following code:

data_phone_new = readLines("data_phone.txt")
gsub("....()......","-",data_phone_new)

CodePudding user response：

We can use sub() as follows:

x <- "0912345678"
output <- sub("(?<=^\\d{4})", "-", x, perl=TRUE)
output

[1] "0912-345678"

CodePudding user response：

We can use groupings. We group the first four characters (^.{4}) and replace it with the same group \\1 plus a -.

sub("(^.{4})", "\\1-", "0912345678")
#> [1] "0912-345678"

^{Created on 2022-10-05 by the reprex package (v2.0.1)}

CodePudding user response：

A non-regex option with stringr::str_sub:

library(stringr)
x <- "0912345678"
str_sub(x, 5, 4) <- '-'

#> x
#[1] "0912-345678"

Or in base R with substring:

paste(substring(x, c(1, 5), c(4, nchar(x))), collapse="-")
#[1] "0912-345678"