Re^4: sort hash of arrays of arrays

[maladav]

in reply to Re^3: sort hash of arrays of arrays
in thread sort hash of arrays of arrays

I'd like to sort the outer arrays of each hash item (1-4) separately, based on the second item of the inner arrays to finally have something like:

{
  1 => [
    [26, 27, 28],
    [16, 17, 18],
    [6, 7, 8],
    [1, 2, 3]
  ],
  2 => [
    [27, 28, 29],
    [17, 18, 19],
    [7, 8, 9],
    [2, 3, 4],
  ],
  3 => [
    [28, 29, 30],
    [18, 19, 20],
    [8, 9, 10],
    [3, 4, 5]
  ],
  4 => [
    [29, 30, 31],
    [19, 20, 21],
    [9, 10, 11],
    [4, 5, 6]
  ],
}

So for the first set, values 2, 7, 17 and 27 were compared to get the right order.
I hope this clarifies my problem.

Thanks

[BrowserUk]

Then you need to do one sort for each key in the hash like this:

@{ $hash{$_} } = sort{ $b->[1] <=> $a->[1] } @{ $hash{$_} } for keys %
+hash;;

pp \%hash;;
{
  1 => [[26, 27, 28], [16, 17, 18], [6, 7, 8], [1, 2, 3]],
  2 => [[27, 28, 29], [17, 18, 19], [7, 8, 9], [2, 3, 4]],
  3 => [[28, 29, 30], [18, 19, 20], [8, 9, 10], [3, 4, 5]],
  4 => [[29, 30, 31], [19, 20, 21], [9, 10, 11], [4, 5, 6]],
}

[maladav]

It's awesome, thank you!
How does it work? Specifically, why does it need the for keys %hash part? How could I sort on the innermost elements (e.g. [26, 27, 28] to get [28, 27, 26]) using the same method?
Thanks very much.

[BrowserUk]

How does it work? Specifically, why does it need the "for keys %hash" part?

Because, as I said, you need to do one sort for each key.

(I don't know how better to explain it than that. )

How could I sort on the innermost elements (e.g. [26, 27, 28] to get [28, 27, 26]) using the same method?

Now you need to do one sort for each sub array, for each key, so you need nested loops:

for my $key ( keys %hash ) {
    for my $aref ( @{ $hash{ $key } } ) {
        @{ $aref } = sort { $b <=> $a } @{ $aref };
    }
}
;;

pp \%hash;;
{
  1 => [[28, 27, 26], [18, 17, 16], [8, 7, 6], [3, 2, 1]],
  2 => [[29, 28, 27], [19, 18, 17], [9, 8, 7], [4, 3, 2]],
  3 => [[30, 29, 28], [20, 19, 18], [10, 9, 8], [5, 4, 3]],
  4 => [[31, 30, 29], [21, 20, 19], [11, 10, 9], [6, 5, 4]],
}