Re: DNA Reverse Complement

I think you'll have a problem with the argument structure:

sub revdnacomp {
  # my $dna = @_;  
  # the above means $dna gets the number of 
  # arguments in @_, since it's a scalar context!

  my $dna = shift; # or   my $dna = shift @_;
  # ah, scalar context of scalar gives expected results.
  # my ($dna) = @_; # would work, too

  my $revcomp = reverse($dna);
  $revcomp =~ tr/ACGTacgt/TGCAtgca/;
  return $revcomp;
}
[download]

but why not allow the complementation over more than one element?

sub revcompl { # operates on all elements passed in
  my (@dna) = @_;
  foreach my $segment (@dna) {
    my $revcomp = reverse($segment);
    $revcomp =~ tr/ACGTacgt/TGCAtgca/;
    push @done, $revcomp;
  }
  return @done; # or reverse @done;  # what's best semantics?
}
[download]

Did I miss anything?

Comment on Re: DNA Reverse Complement Select or Download Code

Replies are listed 'Best First'.
Re^2: DNA Reverse Complement by Aristotle (Chancellor) on Sep 14, 2002 at 05:36 UTC
`sub revcompl { return map { (my $rev = reverse $_) =~ tr/ACGTacgt/TGCAtgca/; $rev + } @_ }` [download] Makeshifts last the longest.	[reply] [d/l]
Re^3: DNA Reverse Complement by Anonymous Monk on Aug 20, 2009 at 17:19 UTC
The above sub does not work	[reply]
Re^4: DNA Reverse Complement by Your Mother (Archbishop) on Aug 20, 2009 at 17:57 UTC
Of course it does. I'm guessing you called it in scalar context and got the count of the transform; e.g., 1. `print revcompl("CGTAGTC"), $/; # GACTACG print scalar revcompl("CGTAGTC"), $/; # 1` [download] There was just a post on this issue this morning: Mini-Tutorial: Scalar vs List Assignment Operator.	[reply] [d/l]