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Re^2: Perl sorting unique values

by BrowserUk (Pope)
on Jun 22, 2011 at 17:01 UTC ( #910940=note: print w/ replies, xml ) Need Help??


in reply to Re: Perl sorting unique values
in thread Perl sorting unique values

The sort-then-uniq strategy will handle data of any quantity and will do so with linear performance.

When will you get it through your thick skull that sorting is not linear; it is O(N log N). And disk sorting slower still.


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Comment on Re^2: Perl sorting unique values
Re^3: Perl sorting unique values
by pr09 (Novice) on Jun 23, 2011 at 05:38 UTC
    Hi All, I used wind's method but with slight modifications as below
    ##########################prints unique and sorted salary use strict; use warnings; my %hash; open my $fh, '<', 'abc.txt' or die $!; while (<$fh>) { chomp; my ($key, $val , $val1) = split '\|'; $hash{$val1}++; } print "$_\n" for sort keys %hash; ----abc.txt------ P|PERL|50000 Paa|JAVA|20000 Poo|VB|10000 AB|SAN|20000 ABCD|CSS|500 PQRS|HTML|200 --The output is-- 10000 200 20000 500 50000
    Though i sorted and printed the unique values,the issue is maybe we may want to print it like
    50000 20000 10000 500 200
    But according to "Perl in 21 days" sort only compares the first digit/letter and sorts accordingly. For printing the above specified output we may want to write a subroutine which compares two values and then swaps them and prints the output. And one more thing, we are not allowed to install CPAN modules in our firm,as we have restricted access.So whatever we do we have to use existing functions and code.
      Got the desired output:
      # use strict; #use warnings; my %hash; open my $fh, '<','abc.txt' or die $!; while (<$fh>) { chomp; my ($key, $val , $val1) = split '\|'; $hash{$val1}++; } @sorted= reverse sort keys %hash; #print "After reverse sorting @sorted\n"; ################sorts and prints the array salaries in descending orde +r for($i=0;$i<=20;$i++) { for($j=$i+1;$j<=20;$j++) { if ($sorted[$i] < $sorted[$j]) { $temp = $sorted[$i]; $sorted[$i] = $sorted[$j]; $sorted[$j] = $temp; } } } print "The salaries in unique and sorted descending order are\n"; print "@sorted\n";
      Thanks All.

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