How to add a column in the data frame within a function

Question

I have a data frame, and I want to do some calculation with existing columns and create new column in my data set which is a combination of existing... I can do this easily

Answer 1

the best approach is to use mutate() from dplyr library. Example:

addcol = function(dat){
    dat1 = mutate(dat, x2=x1*2)
    return(dat1)
}

dat is a data frame with a column named "x1". Use this function addcol(), the new dataset now has a new column named "x2" which is twice the value of "x1", assuming x1 is numeric.