I started to suggest that if both had the (same) IOK or NOK flags set, then use a numeric comparison

but if you are sorting lexicograficaly, you can not compare numbers as numbers because they are not equivalent operations (i.e.: 2 < 10 but 2 gt 10).

It shouldn't be too difficult to write a sorting sub in XS that uses a comparison callback equivalent to the Perl {($c, $d) = ($a, $b); $c cmp $d }. But converting the numbers to strings is an expensive operation, even in C.

Also, you can apply a transformation to the numbers to make them sort lexicograficaly when compared as numbers. For instance, for positive integers with 8 or less digits (untested): 

use Sort::Key 'ukeysort_inplace';
my $digits = 8;
ukeysort_inplace {
  my $a = int $_;
  length $a > $digits and die 'integer $a is too big';
  $a .= ' ' x ($digits - length $a);
  $a =~ tr/ 0123456789/0123456789a/;
  hex $a
} @array;

[download]

(usortkey_inplace should not use more than 8 additional bytes per value on a 32bits machine, update: + 4 bytes for the merge phase of the mergesort)

In reply to Re^7: Howto Avoid Memory Problem in List::MoreUtils by salva
in thread Howto Avoid Memory Problem in List::MoreUtils by Anonymous Monk

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