From: James Edward Gray II <james@...>
Date: 2007-01-11T22:59:00+09:00
Subject: Re: [SUMMARY] Word Blender (#108)

On Jan 11, 2007, at 7:54 AM, Martin DeMello wrote:

> On 1/11/07, Ruby Quiz <james@grayproductions.net> wrote:
>>
>> The main trick used in this recursive grouping of words is the use of
>> "signatures."  A word's signature is just the sorted order of the  
>> letters in the
>> word:  aejms for james, for example.  Comparing signatures makes  
>> it trivial to
>> find words that use the same letters, since their signatures will  
>> be the same.
>>
>> Using the signatures, the choices() method just removes one  
>> character at a time
>> recursing through the word list.  This allows me to find all of  
>> the smaller
>> words that can be formed using the same letters.
>
> I used a different signature method - I mapped each unique letter in
> the target word to a prime, and then used the product of the primes of
> all the letters in a word as its signature. That way, a is contained
> in b if signature(b) % signature(a) == 0, and you can generate the
> signatures via each_byte, array lookup and integer multiplication (no
> need for split, sort or string deletion).

Very interesting.  I've never seen that before.  I like it.

My version of "signatures" comes out of Programming Peals, if my  
memory is right.  Just FYI.

James Edward Gray II