This uses push and unshift as others have advocated. The searching has been moved into a more generic subroutine that takes array references for the array to search and indices array to update, a code reference for the selection criterion, and scalars for how many to look for, starting index and whether to search in reverse.

use strict;
use warnings;

use List::Util qw{ first };

my @dataLines =
   map { [ $_, split m{,|\s} ] }
   <DATA>;

my @indices = ();
push @indices,
   first { $dataLines[ $_ ]->[ 2 ] eq q{Red} }
   0 .. $#dataLines;

findNext(
   \ @dataLines,
   \ @indices,
   sub{ $_[ 0 ]->[ 2 ] eq q{White} },
   4,
   $indices[ -1 ] + 1,
   0 );
findNext(
   \ @dataLines,
   \ @indices,
   sub{ $_[ 0 ]->[ 2 ] eq q{White} },
   4,
   $indices[ 0 ] - 1,
   1 );

findNext(
   \ @dataLines,
   \ @indices,
   sub{ $_[ 0 ]->[ 2 ] eq q{Blue} },
   1,
   $indices[ -1 ] + 1,
   0 );
findNext(
   \ @dataLines,
   \ @indices,
   sub{ $_[ 0 ]->[ 2 ] eq q{Blue} },
   1,
   $indices[ 0 ] - 1,
   1 );

print $dataLines[ $_ ]->[ 0 ] for @indices;

sub findNext
{
    my( 
       $raLookIn,
       $raRecord,
       $rcSelect,
       $howMany,
       $startIdx,
       $reverse ) = @_;

    return if $reverse ? $startIdx < 0 : $startIdx > $#{ $raLookIn };

    for my $idx (
       $reverse
       ? reverse 0 .. $startIdx
       : $startIdx .. $#{ $raLookIn } )
    {
        next unless $rcSelect->( $raLookIn->[ $idx ] );
    if( $reverse )
    {
        unshift @$raRecord, $idx;
    }
    else
    {
        push @$raRecord, $idx;
    }
    return unless -- $howMany;
    }
}

__END__
1.00,Blue,12:00
40.20,White,12:00
80.30,White,12:00
120.00,White,12:00
126.00,White,12:00
162.43,White,12:00
198.86,White,12:00
235.29,White,12:00
271.72,Red,03:45
308.15,White,12:00
344.58,White,12:00
381.01,White,12:00
417.44,White,12:00
453.87,White,12:00
490.30,White,12:00
526.73,White,12:00
563.16,Red,07:45
599.59,White,12:00
636.02,White,12:00
672.45,White,12:00
708.88,White,12:00
745.31,White,12:00
781.74,White,12:00
818.17,White,12:00
854.60,Blue,12:00
891.03,White,12:00
963.89,White,12:00
1000.32,White,12:00
1036.75,Red,08:30
1073.18,White,12:00
1109.61,Red,06:00
1146.04,White,12:00
1182.47,White,12:00
1218.90,White,12:00
18516.40,Blue,12:00
1255.33,White,12:00
927.46,White,12:00

[download]

The output

1.00,Blue,12:00
126.00,White,12:00
162.43,White,12:00
198.86,White,12:00
235.29,White,12:00
271.72,Red,03:45
308.15,White,12:00
344.58,White,12:00
381.01,White,12:00
417.44,White,12:00
854.60,Blue,12:00

[download]

I hope this is of interest.

Cheers,

JohnGG

In reply to Re: Extracting array elements on either side of a match by johngg
in thread Extracting array elements on either side of a match by punkish

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.