CODEWITHSUNDEEP
r
manu p
manu p

Reputation: 985

Extract numbers that appear last in the string

Is there a way to extract numbers from the strings that appear last

asd <- c("asdf sfsfsd54 sdfsdfsdf sdfsdfsf654")
asd1 <- c("asdf sfsfsd54 sdfsdfsdf sdfsdfsf65421")

Expected output

new_asd 
654

new_asd1
65421

Upvotes: 3

Views: 3139

Answers (7)

akrun
akrun

Reputation: 886998

We can also use stri_extract_last_regex from stringi

> library(stringi)
> stri_extract_last_regex(asd, "\\d+")
[1] "654"
> stri_extract_last_regex(asd1, "\\d+")
[1] "65421"

Upvotes: 0

JKupzig
JKupzig

Reputation: 1303

This code extracts always the last numeric entries in a string:

(stringr::str_extract(asd, stringr::regex("(\\d+)(?!.*\\d)")))
"654"
(stringr::str_extract(asd1, stringr::regex("(\\d+)(?!.*\\d)")))
"65421"

If you want to get only the number when the very last character of the string is a number then you could implement a simple ifelse condition to check for that specifically, e.g.:

x<- c("asdf sfsfsd54 sdfsdfsdf sdfsdfsf654f")
ifelse(!is.na(as.numeric(substr(x, nchar(x), nchar(x)))), 
       (stringr::str_extract(x, stringr::regex("(\\d+)(?!.*\\d)"))),
       NA)
NA #returns NA because last entry of string is not numeric ("f")

Upvotes: 4

Michael Dewar
Michael Dewar

Reputation: 3248

A single regex is sufficient for your situation.

stringr::str_extract(asd, "(\\d+$)")

The $ anchors the capture group to the end of the string.

Upvotes: 4

ThomasIsCoding
ThomasIsCoding

Reputation: 101179

If string always ends with digits, then we can try gsub

> x <- c("asdf sfsfsd54 sdfsdfsdf sdfsdfsf654", "asdf sfsfsd54 sdfsdfsdf sdfsdfsf65421")

> gsub(".*\\D", "", x, perl = TRUE)
[1] "654"   "65421"

Upvotes: 0

user438383
user438383

Reputation: 6206

One solution which first splits the string based on whitespace, then gets the last substring and removes any letters. This should work as long as there is only letters and numbers in the strings.

library(stringr)

get_num = function(x) {
    str_remove_all(rev(unlist(str_split(x, " ")))[1], "[a-z]")
}

> get_num(asd)
[1] "654"
> get_num(asd1)
[1] "65421"

Upvotes: 1

Vishal A.
Vishal A.

Reputation: 1381

You can do something like this:

library(stringr)
val <- str_extract_all(asd1, "\\d+")[[1]]
tail(val, 1)
"65421"

OR

as.numeric(gsub("[^\\d]+", "", asd, perl=TRUE))
val <- regmatches(asd1, gregexpr("[[:digit:]]+", asd1))[[1]]
tail(val, 1)
"65421"

Upvotes: 1

Tim Biegeleisen
Tim Biegeleisen

Reputation: 520958

I would use sub combined with ifelse here:

x <- c("asdf sfsfsd54 sdfsdfsdf sdfsdfsf654", "abc", "123")
nums <- ifelse(grepl("\\d$", x), sub(".*?(\\d+)$", "\\1", x), "")
nums

[1] "654" ""    "123"

Upvotes: 1

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