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Re: sort, semi-numeric

by tachyon (Chancellor)
on Jan 02, 2003 at 06:30 UTC ( #223712=note: print w/replies, xml ) Need Help??

in reply to sort, semi-numeric

You are using a Schwartzian Transform which is good. In this example my expensive function splits the name into three parts (word chars, digits or ., and then everything else). split is a good way to do it as 1) if it fails it will return the whole string (so we can sort on that). If it succeeds then we need to remember that it will split at all the number . sequences so we put the string back together after the first split. If we were to use a straight regex here and it failed to match we would need to have all sorts of fallback cases split() handles it neatly.

The sort then proceeds on first bit, numbers, last bit. If you just wanted to sort foo-bar-0.01.tar.gz then you only need to return @bits[0,1] from func() for it to work correctly.

sub sort_n { return map { $_->[0] } sort { $a->[1] cmp $b->[1] || $a->[2] <=> $b->[2] || $a->[3] cmp $b- +>[3] } map { [$_, func($_)] } @_; sub func { my @bits = split /([\d\.]+)/, $_[0]; return @bits[0,1], j +oin '', @bits[2..$#bits] } } my @ary = qw( z1z z2a z2z a1a a2b a1.1a a2.1a a0.1a a0.01a b bbb b2b2b +2b 2b2c a2bc2 ); print "This is what func() does for us\n"; $" = ', '; for (@ary) { my @a = func($_); print "@a\n" } print "\nHere is the sorted list\n"; print "$_\n" for sort_n(@ary); __DATA__ This is what func() does for z, 1, z z, 2, a z, 2, z a, 1, a a, 2, b a, 1.1, a a, 2.1, a a, 0.1, a a, 0.01, a b, , bbb, , b, 2, b2b2b , 2, b2c a, 2, bc2 Here is the sorted list 2b2c a0.01a a0.1a a1a a1.1a a2b a2bc2 a2.1a b b2b2b2b bbb z1z z2a z2z




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