How can I change 0123 into ACTG with tr or Perl?

Question

I have a file with such list:

100
101
102
103

What I want to do is to replace every 0 into A, 1 into C, 2 into G, 3 into T. Hence we hope to get

CAA
CAC
CAG
CAT

Answer 1

You've practically worked out the answer yourself. Simply:

tr 0123 ACGT <input_file >output_file

or:

echo 2033010 | tr 0123 ACGT

Answer 2

Here:

perl -p -e 'tr/0123/ACGT/'

Verification:

$ perl -p -e 'tr/0123/ACGT/' <~/input
CAA
CAC
CAG
CAT

Answer 3

$ echo 3210 | tr 0123 ACGT
TGCA

When not using any options, tr takes two sets of characters, and makes a 1:1 mapping from the first set to the second set. So, as written above, 0 maps to A, 1 maps to C, 2 maps to G, and 3 maps to T.

Answer 4

Just for completeness:

sed 'y/0123/ACGT/' file

Answer 5

   $ awk -vFS="" 'BEGIN{_["1"]="C";_["2"]="G";_["3"]="T";_["0"]="A"}{for(i=1;i<=NF;i++){printf _[$i]}print ""}' file
    CAA
    CAC
    CAG
    CAT