Extracting numbers from vectors of strings

Question

I have string like this:

years<-c(\"20 years old\", \"1 years old\")

I would like to grep only the numeric number from this vector. Expe

Answer 1

Extract numbers from any string at beginning position.

x <- gregexpr("^[0-9]+", years)  # Numbers with any number of digits
x2 <- as.numeric(unlist(regmatches(years, x)))

Extract numbers from any string INDEPENDENT of position.

x <- gregexpr("[0-9]+", years)  # Numbers with any number of digits
x2 <- as.numeric(unlist(regmatches(years, x)))