Re: [xsl] Word Ladders as an example of a "Find shortest path between two nodes in a graph" problem

Subject: Re: [xsl] Word Ladders as an example of a "Find shortest path between two nodes in a graph" problem
From: "Sean B. Durkin" <sean@xxxxxxxxxxxxxxxxx>
Date: Tue, 27 Nov 2012 23:58:58 +1100
Dimitre,

I'm not making any claims about any alternatives being better or worse. I am just offering food for thought.

Faithfully,
Sean.

On 27/11/2012 11:50 PM, Dimitre Novatchev wrote:
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-angry-to-happy-in-20-steps/


Any feedback about this implementation and suggestions for further
optimization are welcome.

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