Formatting phone number based on country code - r

Question

I am working on a shiny app where I want to display telephone numbers of contacts. If the number is a US number, I want to show it in a specific format, for example (XXX) XXX- XXXX else I just want to return the number as it is.
I tried the most simple way using substr. This is the function I have.
telFormat <- function(x){
if (is.na(x)){
return ("")
}
if(substr(x,1,3) %in% c("+1 ")){
p1 <- substr(x,4,6)
p2 <- substr(x,8,10)
p3 <- substr(x, 12,15)
return (paste("(",p1,") ",p2,"-",p3, sep = ""))
}
else
return (x)
}
The sample data I have is:
sample <- c("[phone]", "[phone]", "[phone]",
"[phone]", "[phone]", NA, "[phone]",
"[phone]", "[phone]", "[phone]", "[phone]",
"[phone]", "[phone]", "[phone]", "[phone]",
"[phone]")
The output for the phone numbers starting with +1 gets converted correctly, but there is something wrong with the other numbers.
telFormat(sample)
#output
[1] "[phone]" "[phone]" "( (0) 20- 743" "( (0) 20- 743" "
[phone]" "(NA) NA-NA" "( (0) 20- 591"
[8] "( 2 ) 272-2200" "(2 3) 03 -448" "[phone]" "( (0) 20- 743" "
[phone]" "[phone]" "[phone]"
[15] "[phone]" "[phone]"
and I get this warning message too
Warning messages:
1: In if (is.na(x)) { :
the condition has length > 1 and only the first element will be used
2: In if (substr(x, 1, 3) %in% c("+1 ")) { :
the condition has length > 1 and only the first element will be used
What am I doing wrong here? Is there a efficient way to get the desired output?

Answer 1

If all US numbers in your data have a specific format, i.e. +1 XXX XXX XXXX, you can use regex ^\\+1 (\\d{3}) (\\d{3}) (\\d{4})$ to reformat it:
sub("^\\+1 (\\d{3}) (\\d{3}) (\\d{4})$", "(\\1) \\2-\\3", sample)
# [1] "[phone]" "[phone]" "[phone]"
# [4] "[phone]" "[phone]" NA
# [7] "[phone]" "[phone]" "[phone]"
#[10] "[phone]" "[phone]" "[phone]"
#[13] "[phone]" "[phone]" "[phone]"
#[16] "[phone]"
This uses capture groups with parenthesis to match the first three, second three and last four digits in a US number, refer to these pattern with back references \\ with a number as replacement.

Answer 2

May be somethign like this helps with stringr
library(stringr)
as.data.frame(do.call(rbind, lapply(str_match_all(sample[!is.na(sample)],
"(\\+1|.*)[^\\d]?(\\d+)[^\\d]+(\\d+)[^\\d]+(\\d+)$"), function(x) x[,2:5])))
V1 V2 V3 V4
1 [phone]
2 [phone]
3 [phone]
4 [phone]
5 [phone]
6 [phone]
7 [phone]
8 [phone]
9 [phone]
10 [phone]
11 [phone]
12 [phone]
13 [phone]
14 [phone]
15 [phone]