I have written a perl code for filtering data contained in a file ($input_file_name) based on the filter expression($expr). While doing this, I face some problems. When I hard code the arrays @data and @col in the code, I am getting the results. But the moment I get the arrays @col and @data based on the user input file ($input_file_name) inside the "if" loop, there is no filter. The reason is @data array inside the "if" loop, when accessed outside has only one value and that doesn't satisfy the filter expression. Then I changed it as $array$i. Now I don't know how should I modify
  1. the sub routine sub filterdata
  2. my @result array
  3. print join function
Can some one please suggest me what changes I have to do, so that I can get the results? Any help in this regard is solicited. 
    
#! /usr/bin/perl -w
use strict;            #- matter of style
use warnings;                #- and again

my (@col,@data,$input_file_name,@temp,$header,$data_line,$i);
$input_file_name= "MC_data.dat";

   if (-s $input_file_name ) {
    open(INPUT, $input_file_name) || die "Cannot open: \nReason: $!\n"
+;
            @temp = <INPUT> ;
          chomp @temp;
            $header = shift(@temp);
            $header =~ s/^\s+(.*)/$1/;     #Remove the leading white s
+paces
            @col = split /\s+/, $header;
                
            foreach $i ( 0 .. $#temp ) {
            $data_line = $temp[$i];
    $data_line =~ s/^\s+(.*)/$1/;     #Remove the leading white spaces
    @data = split /\s+/, $data_line;
    $data[$i] = split /\s+/, $data_line;
    }
   }

@col = qw (RUN a1 a2 a3 weight sig1 sig2 sig3);

@data=(
      [qw( 1   0.200000   0.200000   0.200000   0.765685    75881.9
29289.3 -46592.6)],
      [qw( 2   0.200345   0.200000   0.200345   0.966661    75766.0
29268.4 -46497.6)],
      [qw( 3   0.200000   0.200345   0.200000   0.766030    75867.1
29259.8 -46607.4)],
      [qw( 4   0.359575   0.253987   0.359575   1.271019    43898.7
19675.6 -24223.1)],
      [qw( 5   0.359921   0.253987   0.359921   1.271995    43861.3
19666.1 -24195.2)]
);

map{ my $i=$_; no strict 'refs'; *{"filter::$col[$i]"} = sub{$_->[$i]}
+ }
0..$#col;


sub filterdata
{
    my $cref=shift;
    grep &$cref,@_
}


sub filterspec
{
    my $e = shift;
    map{ $e =~ s/\b$_\b/filter::$_()/g } @col;
    eval "sub{ $e }"
}

my $expr = "weight < 1.2 && sig1 > 75800";


my $filter_handler = filterspec( $expr ) or die $@;

my @result = filterdata ($filter_handler,@data);  

print join("$/",map{join(" ",@$_)}@result).$/;

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Edit: Added <code> tags, minor formatting. larsen

In reply to Array accessing by guhan

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