Thanks for the responses everyone,

Incidentally, it is not 'homework'; I am a PhD genome biologist still getting to grips with the finer details of Perl - I am going to use the code as part of a script that will allow me to count genes which are shared across different species. The example I wrote was merely for ease of readership.

So whilst its true that I should learn more about the grep and map functions (although asking questions is part of learning, I think), I'm not skipping my way through some homework assignment.

Thanks again!

It is certainly possible to get a lot done without fancy map statements. There is certainly something to be said for doing something straightforward with foreach loops. Don't worry about being compact/terse - do something that is easy for you to understand - worry about more complex constructs when you are writing a lot more Perl.

See code below. Perl is great at translating one thing into another thing - the hash table. So I just make a hash table table to translate the column name into an array index. This also perhaps could have been just statically declared, but I wanted to make this flexible. For each row in the table, I just zero out an array and use the name2Index translator to turn on the appropriate elements and then print that row.

#!/usr/bin/perl -w
use strict;
use Data::Dump qw(pp);

my $header_row= 'one two three four five';
my %table = (  row_1 => [qw(one five two)],
               row_2 => [qw(four two)],
               row_3 => [qw(three one five four)],
            );
                            
my %name2Index;              

my $col=0;   
foreach my $col_head (split ' ',$header_row)
{
   $name2Index{$col_head} = $col++;
}

print "name2Index table = ",pp(\%name2Index),"\n\n";

foreach my $row (sort keys %table)
{
   my @bitmap = (0) x keys %name2Index;
   
   foreach my $col_name (@{$table{$row}})
   {
      $bitmap[$name2Index{$col_name}] = 1; 
   }
   
   print "$row = @bitmap\n";
}

__END__
name2Index table = { five => 4, four => 3, one => 0, three => 2, two =
+> 1 }

row_1 = 1 1 0 0 1
row_2 = 0 1 0 1 0
row_3 = 1 0 1 1 1
[download]

my $header_row= 'one two three four five';
...
my %name2Index;
...
my $col=0;   
foreach my $col_head (split ' ',$header_row)
{
   $name2Index{$col_head} = $col++;
}
[download]

Or more simply as:

my @header_row = qw/ one two three four five /;
...
my %name2Index;
...
@name2Index{ @header_row } = 0 .. $#header_row;
[download]