Sort a two-dimensional array?

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

I'm trying to sort a two-dimensional array, alphabetically, by just the first column. I've come up with the following, but it doesn't work. It seems to just throw the first row at the end.

I fear it's obvious, but I don't really know what I am doing.

@unsorted_array = ([f, g, h, i, j], 
                   [a, b, c, d, e], 
                   [k, l, o, n, r], 
                   [j, a, o, n, e], 
                   [f, p, r, t, u]);
@big_table_array = sort {uc($a) cmp uc($b)}@unsorted_array;

$output_array_tracker = 0;
while ($output_array_tracker < ($#unsorted_array + 1)){
    print "$big_table_array[$output_array_tracker][0],
               $big_table_array[$output_array_tracker][1], 
               $big_table_array[$output_array_tracker][2], 
               $big_table_array[$output_array_tracker][3], 
               $big_table_array[$output_array_tracker][4], 
               $big_table_array[$output_array_tracker][5]
               \n";
    $output_array_tracker = $output_array_tracker + 1;
    }
[download]

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Re: Sort a two-dimensional array? by gjb (Vicar) on Dec 20, 2002 at 22:14 UTC
`sort {uc($a->[0]) cmp uc($b->[0])} @unsorted_array` should work. Hope this helps, -gjb-	[reply] [d/l]
Re: Re: Sort a two-dimensional array? by Anonymous Monk on Dec 20, 2002 at 22:40 UTC
It does, thanks.	[reply]
Re: Sort a two-dimensional array? by Paladin (Vicar) on Dec 20, 2002 at 22:20 UTC
In your code, `$a` and `$b` are elements of `@unsorted_array` which are arrayrefs. You need to dereference them to get the actual element you want to sort on. `@unsorted_array = ([f, g, h, i, j], [a, b, c, d, e], [k, l, o, n, r], [j, a, o, n, e], [f, p, r, t, u]); @big_table_array = sort {uc($a->[0]) cmp uc($b->[0])} @unsorted_array;` [download]	[reply] [d/l] [select]
Re: Sort a two-dimensional array? by dempa (Friar) on Dec 20, 2002 at 22:14 UTC
In your sort, $a and $b are references to arrays. To access the first row (row 0) you need to dereference the arrays first. Change $a and $b to ${$a}[0] and ${$b}[0] in your sort routine. -- dempa	[reply]
Re: Sort a two-dimensional array? by seattlejohn (Deacon) on Dec 21, 2002 at 04:12 UTC
Others have accurately explained how to get the sort to work the way you want, but I thought this would also be a good opportunity to tell you about the eminently useful Data::Dumper module, which will let you eliminate that unsightly loop at the end of your code. `use Data::Dumper; # ... your sort code here ... print Dumper \@big_table_array;` [download] Data::Dumper is handy to have in your toolbox when it's time for this kind of inspection. $perlmonks{seattlejohn} = 'John Clyman';	[reply] [d/l]