Sorting integer value hash keys

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

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Re: Sorting integer value hash keys by CountZero (Bishop) on Dec 25, 2009 at 16:38 UTC
Because `sort` does an alphabetic sort by default. If you want to do a numerical sort, you must provide the sort routine yourself as a code block: `sort {$a <=> $b} keys %statistics` [download] Try `perldoc -f sort` for more info. CountZero A program should be light and agile, its subroutines connected like a string of pearls. The spirit and intent of the program should be retained throughout. There should be neither too little or too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity." - The Tao of Programming, 4.1 - Geoffrey James	[reply] [d/l] [select]
Re: Sorting integer value hash keys by gube (Parson) on Dec 25, 2009 at 18:08 UTC
`#!/usr/bin/perl my %statistics = ( 1, 0, 2, 0, 3, 0, 4, 0, 5, 0, 6, 0, 7, 0, 8, 0, 9, 0, 10, 0 ); foreach my $statistic (sort {$a <=> $b} keys %statistics) { print $statistic ." ".$statistics{$statistic}. "\n"; } Output: 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 10 0` [download]	[reply] [d/l]
Re^2: Sorting integer value hash keys by JadeNB (Chaplain) on Dec 25, 2009 at 18:53 UTC
Sorry, I can't resist: `my %statistics; undef @statistics{ 1..10 }; # or @statistics{ 1..10 } = (0) x 10 say join "\n", sort { $a <=> $b } keys %statistics;` [download] or, if you don't need a name and like the `0` values: `say join "\n", sort { $a <=> $b } keys %{{ map { $_ => 0 } 1..10 }}` [download]	[reply] [d/l] [select]
Re^3: Sorting integer value hash keys by ikegami (Patriarch) on Dec 25, 2009 at 19:25 UTC
~~You're missing a newline on the last line.~~ `say join "\n", sort { $a <=> $b } keys %{{ map { $_ => 0 } 1..10 }}` [download] ~~should be~~can be shortened to `say for sort { $a <=> $b } keys %{{ map { $_ => 0 } 1..10 }}` [download] Furthermore, since you assume the list is constant, that can be simplified to `say for sort { $a <=> $b } 1..10;` [download] And if you wanted to show that stringification doesn't matter, the following would suffice: `say for sort { $a <=> $b } map "$_", 1..10;` [download]	[reply] [d/l] [select]
Re^4: Sorting integer value hash keys by JadeNB (Chaplain) on Dec 25, 2009 at 19:41 UTC
Re^5: Sorting integer value hash keys by ikegami (Patriarch) on Dec 25, 2009 at 20:01 UTC


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