Sort routine

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

hello

I have an array like the following:

@event_queue = ("$time\tEvent 1", "$time\tEvent 5", "$time\tEvent 3";
[download]

My array will grow to probably 100 elements, with the time element increasing at random, and I want to sort the array in ascending order based on the time portion.

This is currently what I'm doing
[download]

@event_queue = sort { $a <=> $b } @event_queue;

This doesn't seem to work, I'm trying to ignore the Event portion of the array, and sort based on the time portion.

Any suggestions?

Comment on Sort routine Select or Download Code

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Re: Sort routine by Abigail-II (Bishop) on Sep 18, 2002 at 11:45 UTC
Assuming the `$time` part is a Unix timestamp, and all stamps are from after Sun Sep 9 01:46:39 2001, you could simply do: `@event_queue = sort @event_queue`. Otherwise, it depends on the format of `$time`. Abigail	[reply] [d/l] [select]
Re: Re: Sort routine by Anonymous Monk on Sep 18, 2002 at 11:48 UTC
$time isn't a unix time stamp, it's a simple 3 unit time increment (i.e. 3,6,9,)	[reply]
Re: Sort routine by Abigail-II (Bishop) on Sep 18, 2002 at 11:55 UTC
Then you can use a Guttman-Rosler Transform (GRT) or a Schwarzian Transform (ST) in a straightforward way. A search on this site should reveal many examples. Abigail	[reply]
Re: Sort routine by RMGir (Prior) on Sep 18, 2002 at 12:02 UTC
You've got a few options. You can change how you store your data, storing your time values with 0 padding, like this: `sub makeEvent { sprintf("%08d\t%s",@_); } @event_queue = (makeEvent($time,"Event 1"), makeEvent($time,"Event 5") +, makeEvent($time,"Event 5")); # now this works fine! @event_queue=sort @event_queue;` [download] That's actually a variant of a technique called the Guttman Rossler Transform; in the GRT you'd encode your times just before sorting, and decode them after you're done. But if you can just keep them in sortable form all along, life is simpler. The other alternative is the Schwartzian Transform, which is a fraction less efficient, but will still do the job very well... `@event_queue = map { $_->[0] } sort { $a->[1] <=> $b->[1] } map { [$_, (split/\t/)[0]] } @event_queue;` [download] The trick here is that the time values are extracted, and then compared as integers to get things in the right order. Then the strings that were associated with those integers are returned by the top map call. -- Mike	[reply] [d/l] [select]
Re: Sort routine by dada (Chaplain) on Sep 18, 2002 at 11:56 UTC
this seems a perfect case for a Schwartzian Transform: `@event_queue = map { $_->[0] } sort { $a->[1] <=> $b->[1] } map { [$_, split /\t/, $_, 1] } @event_queue;` [download] cheers, Aldo King of Laziness, Wizard of Impatience, Lord of Hubris	[reply] [d/l]
Re^2: Sort routine by Aristotle (Chancellor) on Sep 18, 2002 at 20:09 UTC
You do, of course, mean `map { [$_, split /\t/, $_, 2] }` Makeshifts last the longest.	[reply] [d/l]
Re: Sort routine by Anonymous Monk on Sep 18, 2002 at 12:18 UTC
Thanks guys (and gals), I've never used the transform method, but it works very well, and this is definitely worth commiting to memory.	[reply]


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