skp has asked for the wisdom of the Perl Monks concerning the following question:

Monks, I have a need to search and replace portions of array elements from elements of another array.

I am attempting to split both arrays and splice if there is a match. The ideal output would look like this for the first match of element of @dp2 and 4th of @stu2. I also need to keep intact any non matching elements of @stu.

103_dsu 1 35 nbu103 Disk 6 -1 

@stu = (103_dsu 1 35 nbu103,104_dsu 1 35 nbu104,204_tape 1 1 ACS1,101_
+dsu 1 35 nbu101);

@dp = (nbu103 Disk 6 -1,nbu104 Disk 6 -1,nbu101 Disk 6 -1); 
 
    foreach $var (@stu) {
            foreach $var2 (@dp) {
            @stu2 = split(' ',$var);
            $s1 = $stu2[3];
                @dp2 = split(' ',$var2);      
                $s2 = @dp2[0];
                if ($s1 eq $s2) { 
                splice (@stu2,3,1,$var2);
            }
        }
    }

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Re: Search and Replace Elements from 1 array to another.
by Riales (Hermit) on Apr 03, 2012 at 00:04 UTC

    Does your code compile? O.o

    Anyways, I think you might be overcomplicating things. This seems to do what you want:

    my @stu = (
    '103_dsu 1 35 nbu103',
    '104_dsu 1 35 nbu104',
    '204_tape 1 1 ACS1',
    '101_dsu 1 35 nbu101',
);

my @dp = (
    'nbu103 Disk 6 -1',
     'nbu104 Disk 6 -1',
    'nbu101 Disk 6 -1',
);

foreach my $stu (@stu) {
    my (undef, undef, undef, $possible) = split ' ', $stu;
    my ($matched_dp) = grep {
        my ($dp) = split ' ', $_;
        $dp eq $possible
    } @dp;

    $stu = $matched_dp if $matched_dp;
}

use Data::Dumper;
print Dumper(@stu);

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[reply]
[d/l]

      Thanks! That is what I was looking for. One addition needed is that if a match was found it would replace the match along with the rest of the pre split element if possible.

      Apologies for not wording that better.

      Current output
$VAR1 = 'nbu103 Disk 6 -1';
$VAR2 = 'nbu104 Disk 6 -1';
$VAR3 = '204_tape 1 1 ACS1';
$VAR4 = 'nbu101 Disk 6 -1';

Needed output 
$VAR1 = '103_dsu 1 35 nbu103 Disk 6 -1';
$VAR2 = '104_dsu 1 35 nbu104 Disk 6 -1';
$VAR3 = '204_tape 1 1 ACS1';
$VAR4 = '101_dsu 1 35 nbu101 Disk 6 -1';

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[reply]
[d/l]

        Shouldn't be much of a change. The only somewhat tricky part might be a fancier use of split in order to avoid having to concatenate the first few values together after splitting them previously. I think this should work:

        # Instead of the existing split in the code I wrote...
my ($pre, $possible) = split / ([^ ]+)$/, $stu;

        [download]

        That way, you can just concatenate $pre to the beginning of $matched_dp when you assign to $stu.

        As a sidenote, am I the only one that was surprised to find that Perl does not have an rsplit function? This is possibly the first time I've found myself thinking 'Gee, if this were Python...' :P

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