in reply to Using map and grep to Sort one list using another list

Do you mean like this?
my @result =
  map { my $key = $_; grep m/^\d\|\d\|\d\|$key\|\d$/, @records } @keys
+;

[download]

-M

Free your mind

Replies are listed 'Best First'.
Re^2: Using map and grep to Sort one list using another list
by AntsPants (Novice) on Feb 05, 2007 at 13:52 UTC
    that is what I meant and that is what I tried in testing. see reply to first post ;) As I said, I feel an idiot!!
[reply]
Re^2: Using map and grep to Sort one list using another list
by shmem (Chancellor) on Feb 05, 2007 at 14:05 UTC
    You will have undefined values in your @result array.

    the above is plain wrong--

    --shmem

[reply]
[d/l]
      I don't see that happening. Perhaps I have missed something.

      use strict;
use warnings;

use Data::Dumper;

my @keys = qw{a e i o u};

my @records = qw{
   1|2|3|d|4
   1|2|3|a|4
   1|2|3|d|4
   1|2|3|o|4};

my @result =
   map {
           my $key = $_;
           grep { m{^(?:\d\|){3}$key\|\d$} } @records
       }
   @keys;

my $dd = Data::Dumper->new([\@result], [qw{*result}]);
print $dd->Dumpxs();

      [download]

      produces

      @result = (
            '1|2|3|a|4',
            '1|2|3|o|4'
          );

      [download]

      Cheers,

      JohnGG

[reply]
[d/l]
[select]
      My take on this was rather that when the grep fails to produce a match, it returns an empty list to map which then operates on no extra entries - i.e. doing nothing rather than constructing an undefined value.

      -M

      Free your mind

[reply]

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