Re: Selective Printing of Lines

Had a beer at lunch and don't feel like doing my own work...

use strict ;
use warnings ;

my @data = sort <DATA> ;

my %min ;
foreach (@data) {
  my ($col1, $col2, $col3) = split /\s+/, $_ ;
  $min{$col2} = $col1 if (! defined $min{$col2}) ;
  print $_ if ($col1 eq $min{$col2}) ;
}

__DATA__
-1 2 ereu
1 2 rerer
2 2 rere
3 2 eee
3 2 wwwe
9 2 qqewew
9 2 vvvgf
-1 2 wwwew
4 3 wwew
-9 3 wwss
6 3 jjuu
7 3 kkii
7 3 ggtyu
8 3 ffder
1 4 rrtrr
1 4 rree
[download]

Comment on Re: Selective Printing of Lines Download Code

Replies are listed 'Best First'.
Re^2: Selective Printing of Lines by polsum (Novice) on Sep 16, 2011 at 00:24 UTC
THank you all for excellent replies. All of them are working fine and now I am trying to 'decode' each of them :D. Hi onelesd, Can you please explain the `if (! defined $min{$col2})` part of your code. Ever since you posted this code, I have been banging my head to understand the usage of defined and the unary operator !. Thanks in advance.	[reply] [d/l]
Re^3: Selective Printing of Lines by onelesd (Pilgrim) on Sep 16, 2011 at 04:28 UTC
See: perldoc -f defined `defined EXPR defined Returns a Boolean value telling whether EXPR has a valu +e other than the undefined value "undef".` [download] ! negates the condition, so in natural language the condition is: "`if $min{$col2} is not defined`".	[reply] [d/l] [select]