Hi Loops,
Nice concept of solution, but you are "throwing" away the return values of the map function, so really, I wouldn't build my hash data like this. Moreover, this method is throwing a warnings Argument "\n" isn't numeric in addition ...
I would rather do like so: 

use strict;
use warnings;

my %data;
while(<DATA>){
  my ($key,$value) = split/\s+|,/=>$_,2;
  $data{$key} = $value;
}
print $_,',',$data{0+$_},$/ for qw( 10.1 100.1 25.1 103.1 );


__DATA__
100.1,A ,25, 36,56,89,45,36,56
25.1 ,B,232,565,65,56,56,48,25
103.1,C,25,5,6,9,4,5,56,889,9
10.1,D,5,6,5,8,9,8,12,23,36,6

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In reply to Re^2: arranging the csv file by 2teez
in thread arranging the csv file by Anonymous Monk

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