Sorting an hash of an array by a value in the array

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

Hi,

I've had a search for this and if I've read the answer anywhere I haven't recognised it as such.

I want to sort a hash by its value...but its value is an array. I want to use the first element in that array for sorting.

i.e. to sort a hash by $hash{$key}[0]

It's possible that this is a stupid thing to do and that's why I can't find anything on it.

Anyway, thanks for reading.

MorayJ

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Re: Sorting an hash of an array by a value in the array by BrowserUk (Patriarch) on Jan 12, 2012 at 15:17 UTC
You cannot actually "sort a hash" per se, but you can create an array of the keys in the required order and then use that to iterate the hash: `%h = ( a=>[3,1..4], b=>[2,1..4], c=>[0..4] );; @sortedKeys = sort{ $h{ $a }[0] <=> $h{ $b }[0] } keys %h;; print "$_ : @{ $h{ $_ } }" for @sortedKeys;; c : 0 1 2 3 4 b : 2 1 2 3 4 a : 3 1 2 3 4` [download] With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice. The start of some sanity?	[reply] [d/l]
Re^2: Sorting an hash of an array by a value in the array by Anonymous Monk on Jan 12, 2012 at 16:10 UTC
Great - thanks. Just what I was looking for and relatively straightforward, though I still have to get used to a lot of this hash syntax! Cheers again MorayJ	[reply]
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