Contributed by Anonymous Monk
on May 28, 2000 at 21:42 UTC
Q&A
> sorting
Description: I have an array of arrays which I need to sort according to the value of the second element of the anonymous arrays that are being referenced by the named array. (did that make sense?)
How do I do this exactly?
@array = [8,9,10], [4,5,6], [7,8,9];
# This is the array of arrays I need to sort
# by second elements.
# Magic step goes here....
# I need to end up with an array like @sorted:
@sorted = [4,5,6], [7,8,9], [8,9,10];
Answer: How do I sort a multidimensional arrays? contributed by reptile @array = ([8,9,10], [4,5,6], [7,8,9]);
@sorted = sort { $a>[1] <=> $b>[1] } @array
Updated and fixed thanks merlyn.  Answer: How do I sort a multidimensional arrays? contributed by chromatic To expand a bit on reptile's answer, you can provide your own subroutine reference to sort. In the subroutine, $a and $b are provided and localized special variables used for comparing two elements to each other. In the code snippet, they're array references, and the special arrow notation is just a way of getting at the second element of each. See sort for more details.  Answer: How do I sort a multidimensional arrays? contributed by tlm In answer to the somewhat more difficult question in Answer: How do I sort a multidimensional arrays?:
If you seek a oneliner answer, I don't know what it is, but if you just want to get the job done, then simply transpose the matrix, apply the earlier solution (for ordering according to the nth row elements), and then transpose back. I.e., for the general case of a nonsquare matrix,
sub transpose {
map {
my $j = $_;
[ map $_[$_][$j], 0..$#_ ]
} 0..$#{$_[0]};
}
my @array = ([8, 9, 10], [6, 5, 4], [7, 8, 9]);
my @sorted =
transpose
sort { $a>[1] <=> $b>[1] }
transpose @array;
kj
 Answer: How do I sort a multidimensional arrays? contributed by flope What about to sort a multidimensional array using the elements of @{$array[1]}?
@array = [8,9,10], [6,5,4], [7,8,9];
@sorted = [10,9,8], [4,5,6], [9,8,7];

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