r - Extracting century and year from a string

Question

I have a large column displaying a string such as:

20-1843PA-HY-4563-214DF

The "20" is the century while the "18 is the year. What is the simplest way to extract these two using a function and have an output of 2018 in R?

Answer 1

We can use sub to capture the digits as a group from the start (^) of the string followed by the -, then capture the two digits ((\d{2})) and replace with the backreference (\1\2) of the captured group

f1 <- function(nm) as.numeric(sub("^(\d+)-(\d{2}).*", "\1\2", nm))
f1(str1)
#[1] 2018

data

str1 <- "20-1843PA-HY-4563-214DF"