rchou2 has asked for the wisdom of the Perl Monks concerning the following question:

Hi, I have a script that prints outputs into a temp file that looks like this: name x y z abc 1 4 3 xyz 2 8 5 I want to sort the temp file and print the values onto another file "values", with descending order based on z. so output would look like: name x y z xyz 2 8 5 abc 1 4 3 Thanks

Replies are listed 'Best First'.
Re: File Sorting
by bronto (Priest) on Jul 19, 2002 at 16:06 UTC

    Could you please read the Site How To and post at least one decently formatted question please? Thanks!

    Frankly speaking, your descending order based on z seems a quite random order: I really can't see which sorting algorithm you used to obtain x y z xyz 2 8 5 abc 1 4 3 from x y z abc 1 4 3 xyz 2 8 5

    This quick-and-dirty (and ***untested***) snippet does a standard reverse sort: you can take it and adapt it for your needs.

    use strict ;
use warnings ;

my $tempfile = "temp_file_name.txt" ;
my $outfile  = "/path/to/values" ;

open IN, $tempfile or die $! ;
open OUT, $outfile or die $! ;

while (<IN>) {
  chomp ;
  my ($name,@values) = split ;
  print OUT join(" ",$name,reverse sort @values),"\n" ;
}

close OUT ;
close IN ;

    [download]

    Ciao!
    --bronto

    # Another Perl edition of a song:
# The End, by The Beatles
END {
  $you->take($love) eq $you->made($love) ;
}

[reply]
[d/l]
[select]
Re: File Sorting
by broquaint (Abbot) on Jul 19, 2002 at 16:25 UTC
    Firstly parse the temp file 
    open(my $fh, "tempfile") or die("ack - $!");
chomp( my $header = <$fh> );
my(undef, @headers) = split ' ', $header;

my(%cols) = do {
    my $i = 0;
    map { $_ => $i++ } @headers;
};

my %info;
while(<$fh>) {
    chomp;
    next if m< ^ \s* \z >x;
    my($name, @rows) = split;
    push @{ $info{$name} }, @rows;
}
close $fh;

    [download]
    Then sort on the 'z' column 
    open(my $fh, ">", "output") or die("ack - $!");
print $fh $header;
print $fh "$_ @{ $info{$_} }\n" for reverse sort {
    $info{$a}->[ $cols{z} ] <=> $info{$b}->[ $cols{z} ]
} keys %info;
close $fh;

    [download]
    Of course a much better idea would be to use one of the CSV type modules such as tilly's Text::xSV or Text::CSV_XS.
    HTH

    _________
    broquaint

    update: changed header regex => split, as I had a bad meme about multiple matches pushing onto the return list, unfortunately not e.g 

    my(@list) = "foo bar baz" =~ m< (?: (\w+) \s* )+ >x;
print "@list";

__ouput__

baz
# not - foo bar baz

    [download]

    update 2: posting on a Friday != a good idea 

    my(@list) = "foo bar baz" =~ m< (\w+) [ ]? >xg;
print "@list";

__output__

foo bar baz

    [download]
    the previous example not working presumably because it was missing the g modifier, and the subsequent captures over-rode the previous one.
[reply]
[d/l]
[select]

      WOW!

      package Bronto ;

use Parser::Rchou2 ;

our $broquaint = Parser::Rchou2->new(node_id => 183282) ;

      [download]

      You will get a ++ from me tomorrow, one + for the script and one for the translation of rchou2's post ;-)

      Ciao!
      --bronto

      # Another Perl edition of a song:
# The End, by The Beatles
END {
  $you->take($love) eq $you->made($love) ;
}

[reply]
[d/l]
      i run into a prolem if the file has three columns, the first is a name (string), the second and third are numerical, then how would i sort it based on the third column in descending value?
[reply]

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