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(tye)Re2: Sorting by_number

by tye (Sage)
on Sep 15, 2001 at 22:24 UTC ( #112643=note: print w/replies, xml ) Need Help??

in reply to Re: (tye)Re: Sorting by_number
in thread Sorting by_number

Yes, for more robust versions of this, see the previously mentioned link.

Actually, dealing with non-negative integers beyond 2**32 or even that won't fit in a double (either accurately or at all) is rather easy. For example, ignoring the case of extra leading zeros again:

my @sorted= grep { s#0.{4}(\d+)#$1#gs; 1 } sort grep { s#(\d+)#"0".pack("N",length$1).$1#ge; 1 } @{[ @list ]};
This deals with any sequence of nearly 2**31 digits (I won't commit beyond that because I'm not certain that all ports of Perl will have a length function that works beyond that -- not that even 2**31 is much of a practical limitation).

Note that it preserves leading zeros unlike the previous one-liner, but it doesn't sort them intuitively. To deal with extra leading zeros properly requires a bit more work, for example:

my @sorted= grep { s#0.{4}(\d+),(0*)!#$2$1#gs; 1 } sort grep { s#(0*)(\d+)#"0".pack("N",length$2)."$2,$1!"#ge; 1 } @{[ @list ]};

Also note that I intentionally did not use a Schwartzian Transform as it is rather slower and uses more memory.

        - tye (but my friends call me "Tye")

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