A hash isn't appropriate, because nothing is guaranteed to be unique (as far as you've let on). You also ask to sort, and hashes are unordered. 

my @unsorted_data;
while (<DATA>) {
   my @fields = /([\d.]+)/g or next;
   push(@unsorted_data, \@fields);
}

my @sorted_data = sort {  $a->[1] <=> $b->[1]
                       || $a->[0] <=> $b->[0] } @unsorted_data;

print("(($_->[0] $_->[1]) ($_->[2] $_->[3]))\n")
   foreach @sorted_data;

[download]

Update: Tested. Fixed the print.

Update: Fixed the error discussed below.

In reply to Re: Sorting large sets of geometric coordinates by ikegami
in thread Sorting large sets of geometric coordinates by Anonymous Monk

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