Re^2: Sorting records on a single field

You can get rid of the reverse operation just inverting the order of the comparison operands. In other words, instead of reverse sort { $a <=> $b } @data use sort { $b <=> $a } @data.

In OP case:

@SortedData = sort { (split (/:/, $b))[-1] <=> (split (/:/, $a))[-1] }
+ @Data;
[download]

Using reverse also makes the sort operation unstable (entries with equal sorting keys do not keep their relative positions after the sort operation).

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Re^3: Sorting records on a single field by Lain78 (Initiate) on Jan 21, 2010 at 11:07 UTC
I see that switching the opereands is better but I don't catch what you mean with "equal sorting keys do not keep their relative positions after the sort operation"... probably I miss something. Could you explain deeply that point? Thanks.	[reply]
Re^4: Sorting records on a single field by salva (Canon) on Jan 21, 2010 at 11:28 UTC
Sure! Let me do it with an example: `my @data = qw(1a 1b 2a 2b); my @s1 = reverse sort { $a <=> $b } @data; my @s2 = sort { $b <=> $a } @data; print "@s1\n@s2\n";` [download] generates: `2b 2a 1b 1a 2a 2b 1a 1b` [download] Note how in the second row, elements with the same sorting key (the numeric part) appear in the same order they had in `@data` while in the first row, corresponding to the `reverse` solution, they do not.	[reply] [d/l] [select]