Difference between numbers on a string

Question

I have a vector

 numbers <- c("25", "22|9", "2|5", "23|7" , "25|15")

I need to find the difference between numbers on the left and right of "|"

The result should be

c(25, 13, -3, 16, 10)

Answer 1

If you ever told me I'll be using eval(parse()), I would have laughed my ass off, yet here it is.

numbers <- c("25", "22|9", "2|5", "23|7" , "25|15")
numbers <- gsub("\\|", "-", numbers)
sapply(numbers, FUN = function(x) eval(parse(text = x)))

   25  22-9   2-5  23-7 25-15 
   25    13    -3    16    10 

That being said:

> require(fortunes)
> fortune("parse")

Personally I have never regretted trying not to underestimate my own future stupidity.
   -- Greg Snow (explaining why eval(parse(...)) is often suboptimal, answering a question triggered by the infamous fortune(106))
      R-help (January 2007)