OpenEuphoria

Re: print.e and Other Questions

• Posted by euman at bellsouth.net Mar 04, 2002
• 390 views

Sorry bout that CK,

I only used print.e to look at the output in an external file.
so its safe to comment this line out.
or you can download the include here:
http://www.rapideuphoria.com/print.zip

Derek more than answered the Q? about hash routines.
BIG D's the man!

Euman
euman at bellsouth.net

Q: Are we monetarily insane?
A: YES
----- Original Message ----- 
From: "Derek Parnell" <ddparnell at bigpond.com>
To: "EUforum" <EUforum at topica.com>
Sent: Tuesday, March 05, 2002 12:08 AM
Subject: Re: print.e and Other Questions


> 
> 5/03/2002 2:51:28 PM, "C. K. Lester" <cklester at yahoo.com> wrote:
> 
> >
> >Where can I get print.e?
> >
> >From the RDS Contributions page, I guess. It is a replacement to Euphoria's
> >print() routine.
> 
> >How do I use Euman's hash table? 
> 
> It gives you a fast way on knowing if a given word is in the words.txt file or
> not.
> 
> You use it by calculating the 'hash' value for the word you are checking on,
> then scan through the
> sequence referenced by the first letter of the word and its length, looking to
> see if the hashvalue
> is there. If so, then the word is in the dictionary, otherwise it is not.
> 
>    Eg.
> 
> theWord = upper(theWord)
>       hv = EumsHash(theWord)
>       l = theWord[1] - 'A' + 1
>       s = length(theWord)
>       inDict = 0
>       for i = 1 to length(hash_table[l][s]) do
>           if hash_table[l][s][i] = hv then
>                -- Word is in dict.
>               inDict = 1
>               exit
>           end if
> end for
> 
> >Or, rather, what structure is it? 
> 
> It is a three-level sequence. The first level represents the letters of the
> alphabet. It is used to
> group the dictionary words by their initial letter.  The second level, that's
> the level within each
> initial letter, represents word length. This sorts all words that start with
> the same letter into
> word size. The third level is just a list of hash values for the dictionary
> words.
> 
> >I'll be looking at it tonight, 
> 
> Have fun.
> 
> >but maybe somebody can give me a general idea about hash tables.
> 
> The general idea behind hashing is to calculate a single value for an item,
> based on attributes of
> the item. Then use this value as a sort of index to speed up searches for the
> item. It is often used
> in compilers and other word-processing programs that have to keep track of
> individual words.
> 
> A common method is to add up the ASCII values of each letter, divide this by
> the number of "bins"
> you have and use the remainder to select a bin to put the word into. If you
> have a huge list of
> words, this is one method of effectively reducing the number of words you have
> to scan through to
> find the one you're after.
> 
>    Example:  Assume I have 5 bins, numbered 0 to 4.
> 
>      word          hashvalue        bin
>     "CAT"            24              4
>     "KANGAROO"       82              2
>     "DOG"            26              1
>     "ELEPHANT"       80              0
>     "LEOPARD"        71              1
> thus "DOG" and "LEOAPARD" would both go in bin#1, but the others would only
> have one word in them.
> 
> The hard part is getting a good enough hashing algorithm that spreads the
> indexes evenly over the
> bins.
> 
> ---------
> Cheers,
> Derek Parnell 
> ICQ# 7647806
> 
> 
> 
>