I’m using stringr in R to try and extract the date from a programme title.

The strings I’m trying to extract from take two forms “The Anonymous Project 2021/22” or “The Anonymous Project (2020/21)”.

I’ve written numerous regular expressions using online tools that say they should work, but I consistently get the output “2020/20” or “2021/20”.

See below for some of the things I’ve tried, all of which return either NA or “2020/20”

I’m absolutely baffled as to what I’m doing wrong. I’m aware there are much simpler ways of getting this data, but I’d really like to understand how I would achieve this, and what’s wrong with my current approach.

My first attempt

Test <- str_extract(df$`title`,'([0-9]{4}[/][0-9]{2})')

Returns “2020/20” and “2021/20”

Grouping the slash with the 2 digit element

Test <- str_extract(df$`title`,'([0-9]{4}([/][0-9]{2}))'))

Returns “2020/20” and “2021/20”

Were the brackets messing me up?

Test <- str_extract(df$`title`,'[0-9]{4}[/][0-9]{2}')

Returns “2020/20” and “2021/20”

Digits instead of the range

Test <- str_extract(df$`title`,'([:digit:]{4}[/][:digit:]{2})')

Returns “2020/20” and “2021/20”

Start and end string markers, just gives me an NA

Test <- str_extract(df$`title`,'^([0-9]{4}[/][0-9]{2})$')