I have a vector of strings with the following format "IN_D44_A09_ET" and I would like to extract the number 9 using the stringr package.
I have been trying to solve it using str_extract(), but I don't get how to formulate the pattern.
values <- c("IN_D44_A09_CT", "XE_D34_A15_ET")
str_extract(values, "_A(\\d+)")
This pattern extracts "_A09" and "_A15" but what I want is "9" and "15".
You can try sub
sub(".*_A0*(.*)_.*","\\1",values)
#[1] "9" "15"
You can use lookbehind pattern -
as.integer(stringr::str_extract(values, '(?<=A)\\d+'))
#[1] 9 15
One way could be to use str_extract twice. In the first str_exract whatever output you are getting, store it as a vector and run str_extract again to get the desired output.
Here's how you could do it:
values <- c("IN_D44_A09_CT", "XE_D34_A15_ET")
temp <- str_extract(values, "A(\\d+)")
str_extract(temp, "(\\d+)")
library(stringr)
values <- c("IN_D44_A09_CT", "XE_D34_A15_ET")
str_match(values, 'A(\\d+)')[, 2]
#> [1] "09" "15"
Created on 2022-01-22 by the reprex package (v2.0.1)
If we want to remove the zeros:
library(stringr)
values <- c("IN_D44_A00090_CT", "XE_D34_A0015_ET")
str_match(values, 'A(\\d+)')[, 2] %>% str_replace('^0+', '')
#> [1] "90" "15"
Created on 2022-01-22 by the reprex package (v2.0.1)
