Complement a DNA sequence

Question

Suppose I have a DNA sequence. I want to get the complement of it. I used the following code but I am not getting it. What am I doing wrong ?

s=readline()
AT         


        

Answer 1

Here a answer using base r. Written with a horrible formatting to make things clear and to keep it as a one-liner. It supports upper and lower cases.

revc = function(s){
       paste0(
           rev(
            unlist(
             strsplit(
                chartr("ATGCatgc","TACGtacg",s)
                      , "")                        # from strsplit
                   )                               # from unlist
               )                                   # from rev
             , collapse='')                        # from paste0
       }