Writing a function to return the nth group of numbers in a phone number

Question

For example, function should be: function_name(phonenumber, n)

function_name(123-456-7890, 1) should return 123
function_name((123)-456-7890, 3) should return 7890

What did you try? Where are you getting stuck? How many different number types do you need to match? Does this help give you a start: https://stackoverflow.com/questions/31172751/extracting-phone-number-issue-in-r — MrFlick, Apr 26 '20 at 21:57
broncos24, you are welcome on SO, but you are starting to show a pattern that is not really aligned to the "norm" on StackOverflow (at least within [tag:r] channels). (1) Please *accept* answers (not just upvoting them). (2) Do some research on your own first, please do not treat "asking a question on SO" as your first web-search. (3) When you do ask a question, please provide (much) more than just terse requirements, including sample data, intended output, and the code you've attempted before now. You're very welcome here, but please respect our volunteered time. — r2evans, Apr 27 '20 at 22:12

score 3 · Answer 1 · answered Apr 26 '20 at 21:57

3

function_name <- function(phone, n) Filter(nzchar, strsplit(phone, "\\D+")[[1]])[n]
function_name("123-456-7890", 1)
# [1] "123"
function_name("(123)-456-7890", 3)
# [1] "7890"

answered Apr 26 '20 at 21:57

r2evans

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score 3 · Answer 2 · answered Apr 26 '20 at 22:00

3

One base R option is using regmatches

function_name <- function(phonenumber, n) regmatches(phonenumber,gregexpr("\\d+",phonenumber))[[1]][n]

answered Apr 26 '20 at 22:00

ThomasIsCoding

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I think this one is likely a little more robust to strings that don't look like phone numbers. – r2evans Apr 26 '20 at 22:17

akrun · Answer 3 · 2020-04-26T22:59:42.650

1

We can split by - and then extract the 'nth' group

f1 <- function(phonenumber, n){
             setdiff(strsplit(phonenumber, '[[:punct:]]+')[[1]], "")[n]
    }

f1('123-456-7890', 3)
#[1] "7890"

f1('(123)-456-7890', 3)
#[1] "7890"

edited Apr 26 '20 at 22:59

answered Apr 26 '20 at 21:57

akrun

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@broncos24 sorry, didn't see that case. Updated the post. thanks for notifying – akrun Apr 26 '20 at 22:59
is there a way to do it with str_detect or str_view – Apr 27 '20 at 02:07

score 1 · Answer 4 · answered Apr 27 '20 at 04:27

1

You can either use \\w+ or \\d+ :

get_nth_group <- function(x, n) stringr::str_extract_all(x, '\\w+')[[1]][n]

get_nth_group("123-456-7890", 1)
#[1] "123"

get_nth_group("(123)-456-7890", 3)
#[1] "7890"

answered Apr 27 '20 at 04:27

Ronak Shah

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score 0 · Answer 5 · answered Apr 27 '20 at 09:10

I would suggest something like this:

library(tidyverse)

get_phone_group <- function(phonenum, n) {
  str_extract_all(phonenum, "\\d+", simplify = TRUE)[, n]
}

get_phone_group("123-456-7890", 1)
#> [1] "123"
get_phone_group("(123)-456-7890", 3)
#> [1] "7890"
get_phone_group(c("345-169-234", "(123)-456-7890"), 3)
#> [1] "234"  "7890"

^{Created on 2020-04-27 by the reprex package (v0.3.0)}

Note that the resulting function is vectorized and therefore nice to use in e.g. a mutate context.

Writing a function to return the nth group of numbers in a phone number

5 Answers5