Re: Word Ladders as an example of a "Find shortest pat

On Tue, Nov 27, 2012 at 3:47 AM, Sean B. Durkin <sean@xxxxxxxxxxxxxxxxx>
wrote:
> Dimitre,
>
> In relation to the XPath 3.0 implementation of *my:HammingDistance*, here
> are two alternatives.
>
> _Alternative 1:__
> _
> fn:fold-left(
>   0,
>   function($distance, $code-diff)
>     {
>       if ($code-diff) then $distance + 1
>                       else $distance
>     },
>   let $c1 := string-to-codepoints($pStr1),
>       $c2 := string-to-codepoints($pStr1) return
>   for $i in 1 .. min(count($c1),count($c2)) return
>     $c1[$i] - $c2[$i]
>   )
>
> __Alternative_ 2:__
>
> _count(
>   let $c1 := string-to-codepoints($pStr1),
>       $c2 := string-to-codepoints($pStr1) return
>   for $i in 1 .. min(count($c1),count($c2)) return
>     1[$c1[$i] eq $c2[$i]]
>     )
>
> The count() function in alternative 2 could equally well be sum().
>
> I'm not making any claims about the relative merits of these alternatives
--
> just providing some food for thought.


Sean,

Why do you think these are better than:

<xsl:sequence select=
      bcount(map-pairs(f:eq#2,
                                  string-to-codepoints($pStr1),
                                  string-to-codepoints($pStr2)
                                  )
                                  [not(.)]
                     )
    b/>


?


I am planning on what I hope will be significantly optimized Hamming
distance implementation -- probably in a next post.

Cheers,
Dimitre



>
> Faithfully,
> Sean B. Durkin
>
>
>
> On 27/11/2012 4:08 PM, Dimitre Novatchev wrote:
>>
>> Dear XSLT professionals,
>>
>> In case you are interested in solving the Word Ladders problem first
>> formulated by Lewis Carroll, or just in an XSLT solution of the "Find
>> shortest path in graph" problem, you might be interested to have a
>> look at the implementation in my latest blog post:
>>
>>
>>
http://dnovatchev.wordpress.com/2012/11/26/word-ladders-or-how-to-go-from-ang
ry-to-happy-in-20-steps/
>>
>> Any feedback about this implementation and suggestions for further
>> optimization are welcome.
>



--
Cheers,
Dimitre Novatchev
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