Extract Phone Numbers from a string in R

Question

I am working on extraction from a text - using 'stringr' package in R.I found this example:

strings <- c(" 219 733 8965", "329-293-8753 ", "banana", "595 794 7569",
"387 287 6718", "apple", "233.398.9187 ", "482 952 3315",
"239 923 8115", "842 566 4692", "Work: 579-499-7527", "$1000",
"Home: 543.355.3679")
pattern <- "([2-9][0-9]{2})[- .]([0-9]{3})[- .]([0-9]{4})"
str_extract(strings, pattern)
str_extract_all(strings, pattern)

However my string is in the below format:

strings <- c("87225324","65-62983211","65-6298-3211","8722 5324","(65) 6296-2995","(65) 6660 8060","(65) 64368308","+65 9022 7744","+65 6296-2995","+65-6427 8436","+65 6357 3323/322")

But i am not sure about the pattern to extract all the above format.Any help would be great.

Answer 1

The code below covers the cases in your question. Hopefully, you can generalize it if you find other character combinations in the data.

# Phone numbers (I've added an additional number with the "/" character)
strings <- c("87225324","65-62983211","65-6298-3211","8722 5324",
           "(65) 6296-2995","(65) 6660 8060","(65) 64368308","+65 9022 7744",
           "+65 6296-2995","+65-6427 8436","+65 6357 3323/322", "+65 4382 6922/6921")

# Remove all non-numeric characters except "/" (your string doesn't include any
# text like "Work:" or "Home:", but I included a regex to deal with those cases
# as well)
strings.cleaned = gsub("[- .)(+]|[a-zA-Z]*:?","", strings)

# If you're sure there are no other non-numeric characters you need to deal with 
# separately, then you can also do the following instead of the code above: 
# gsub("[^0-9/]","", strings). This regex matches any character that's not 
# a digit or "/".

strings.cleaned
 [1] "87225324"       "6562983211"     "6562983211"     "87225324"       "6562962995"    
 [6] "6566608060"     "6564368308"     "6590227744"     "6562962995"     "6564278436"    
[11] "6563573323/322" "6543826922/6921"

# Separate string vector into the cleaned strings and the two "special cases" that we 
# need to deal with separately
special.cases = strings.cleaned[grep("/", strings.cleaned)]
strings.cleaned = strings.cleaned[-grep("/", strings.cleaned)]

# Split each phone number with a "/" into two phone numbers
special.cases = unlist(lapply(strsplit(special.cases, "/"), 
                          function(x) {
                            c(x[1], 
                            paste0(substr(x[1], 1, nchar(x[1]) - nchar(x[2])), x[2]))
                          }))
special.cases
[1] "6563573323" "6563573322" "6543826922" "6543826921"

# Put the special.cases back with strings.cleaned
strings.cleaned = c(strings.cleaned, special.cases)

# Select last 8 digits from each phone number
phone.nums = as.numeric(substr(strings.cleaned, nchar(strings.cleaned) - 7, 
                                                nchar(strings.cleaned)))
phone.nums
 [1] 87225324 62983211 62983211 87225324 62962995 66608060 64368308 90227744 62962995 64278436
[11] 63573323 63573322 43826922 43826921

Answer 2

The pattern argument accepts any regular expression. So if you use for instance str_extract_all(strings, pattern) inserting the regular expression "[0-9]" (which extracts any numeric portions of the string) into the pattern argument will return a list of just the numbers from each element with the element from strings. Other examples of regular expressions may be found here: https://docs.python.org/2/library/re.html.

This is what would be returned from your vector string by using "[0-9]" as the regular expression:

str_extract_all(strings,"[0-9]")

[[1]]
[1] "8" "7" "2" "2" "5" "3" "2" "4"
[[2]]
[1] "6" "5" "6" "2" "9" "8" "3" "2" "1" "1"
[[3]]
[1] "6" "5" "6" "2" "9" "8" "3" "2" "1" "1"
[[4]]
[1] "8" "7" "2" "2" "5" "3" "2" "4"
[[5]]
[1] "6" "5" "6" "2" "9" "6" "2" "9" "9" "5"
[[6]]
[1] "6" "5" "6" "6" "6" "0" "8" "0" "6" "0"
[[7]]
[1] "6" "5" "6" "4" "3" "6" "8" "3" "0" "8"
[[8]]
[1] "6" "5" "9" "0" "2" "2" "7" "7" "4" "4"
[[9]]
[1] "6" "5" "6" "2" "9" "6" "2" "9" "9" "5"
[[10]]
[1] "6" "5" "6" "4" "2" "7" "8" "4" "3" "6"
[[11]]
[1] "6" "5" "6" "3" "5" "7" "3" "3" "2" "3" "3" "2" "2"