[Tutor] First real script

[Danny Yoo]

On Mon, 6 Nov 2006, Carlos wrote:

> This is my first script, I mean the first that I'm trying to do on my 
> own. Its a very simple Cellular Automata thing, the idea is that the 
> initial list A_List is rewritten based on some rules, in this case 
> Wolfram's rule 30. You can modify the list length and its initial state, 
> you can also set the number of iterations.

Hi Carlos,

Cool.  I did something like this a while ago too!

     http://mail.python.org/pipermail/tutor/2002-September/017256.html


Looking at your code, the only suggestion I could make is to encode the 
rules into some kind of lookup structure.  That is, the block:

>            if a == 1 and b == 1 and c == 1:
>                    X = 0
>            elif a == 1 and b == 1 and c == 0:
>                    X = 0
>            elif a == 1 and b == 0 and c == 1:
>                    X = 0
>            elif a == 1 and b == 0 and c == 0:
>                    X = 1
>            elif a == 0 and b == 1 and c == 1:
>                    X = 1
>            elif a == 0 and b == 1 and c == 0:
>                    X = 1
>            elif a == 0 and b == 0 and c == 1:
>                    X = 1
>            elif a == 0 and b == 0 and c == 0:
>                    X = 0

could be tweaked to be more compact.  Conceptually, it takes in three 
values (X, Y, Z), and returns a result in X.  If we look at it in a 
different light, that's a key->value lookup, where the "key" is going to 
be a 3-tuple.

So you can encode the guts of rule 30 with a dictionary:

     rule_30 = {
       (1, 1, 1) : 0,
       (1, 1, 0) : 0,
       (1, 0, 1) : 0,
       (1, 0, 0) : 1,
       (0, 1, 1) : 1,
       (0, 1, 0) : 1,
       (0, 0, 1) : 1,
       (0, 0, 0) : 0,
     }

After we have this, the assignment to X looks much more simple:

     X = rule_30[x, y, z]


Good luck!