in reply to Regular expression for a comma separated string


Hopefully this does the trick for you, using negative lookahead to make sure each character doesn't repeat before the comma (or end of string):

my @tst = qw( A,G AG,CT TC,CA GAT,CGA CGAT,TG ,G ACGT X,A AA,G AC,GGC ATGA,TGG ATCXG,AAC ); for (@tst) { my $side = qr/(?:([ACGT])(?![^,]*\g{-1}))+/; print $_ . (/^$side,$side$/ ? ' good' : ' bad') . $/; }
A,G good AG,CT good TC,CA good GAT,CGA good CGAT,TG good ,G bad ACGT bad X,A bad AA,G bad AC,GGC bad ATGA,TGG bad ATCXG,AAC bad

Oops, more test coverage showed an issue. Needed to use relative group instead of "\1" as originally posted which had a problem with "AC,AC". Fixed.