Delete a period and a number at the end of a character string

Question

How do I delete a trailing period (.) followed by a number (one or two digits in length) directly preceding it? Example:

z <- c("awe", "p.56.red.45", "ted.5", "you.88.tom") 

I only want to remove the .45 and the .5.

Answer 1

You just need a simple regular expression:

z_new = gsub("\\.[0-9]*$", "", z)

A few comments:

1. The first argument in gsub is the pattern we are looking for. The second argument is what to replace it with (in this case, nothing).
2. The $ character looks for the pattern at the end of the string
3. [0-9]* looks for 1 or more digits. Alternatively, you could use \\d* or [[:digit:]]*.
4. \\. matches the full stop. We need to escape the full stop with two slashes.