r - Applying gsub to various columns

Question

What is the most efficient way to apply gsub to various columns? The following does not work

x1=c("10%","20%","30%")
x2=c("60%","50%","40%")
x3 = c(1,2,3)
x = data.frame(x1,x2,x3)
per_col = c(1,2)
x = gsub("%","",x[,per_col])

How can I most efficiently drop the "%" sign in specified columns. Can I apply it to the whole dataframe? This would be useful in the case where I don't know where the percentage columns are.

Answer 1

You can use apply to apply it to the whole data.frame

apply(x, 2, function(y) as.numeric(gsub("%", "", y)))
     x1 x2 x3
[1,] 10 60  1
[2,] 20 50  2
[3,] 30 40  3