Re: food on unoccupied blocks

[Paul E Johnson]

Stacy Oerder wrote:
> I've built a swarm model that does the following, it creates a world
> with a specific size and then places a few bugs on the world at random
> sights.
 ^^^^^^^^
  sites :)
> Thanks
> Stacy Oerder
>
> //Prey.m        
>
> #import "Prey.h"
> #import <random.h>
> #import <space/Discrete2d.h>
>
> @implementation Prey
>
>
> -setWorld: w Food: f {
>         world = w;
>         food = f;
>         return self;
>         
> }
>
> -createEnd {
>         [super createEnd];
>         worldXSize = [world getSizeX];
>         worldYSize = [world getSizeY];
>         return self;
> }
>
> -setX: (int) x Y: (int) y {
>         xPos = x;
>         yPos = y;
>         stepNumb = 0;
>         return self;
>
> }
>
>
> -step {
>
>         int pos;
>         
>         haveEaten = 0;
>         origFood = 1000;
>         amountEaten = 350;
>         extraFood = 100;
>         stepNumb++;
>         
> 	foodHere = [food getValueAtX: xPos Y: yPos];  
> 	printf("foodhere - prey %d \n", foodHere);
>         if ((foodHere) >= amountEaten) {
>                 printf("There is enough food to eat \n");
>                 amountLeft = foodHere - amountEaten;
>                 haveEaten =1;}
>                 else
>                         {
>                         amountLeft = foodHere;
>                         }
>                 printf("The food left - prey %d \n", amountLeft);
>         
>         //bug moves sequentially through world  
>         newX = xPos + 1;        
>         newY = yPos;
>         if (newX >= worldXSize) {
>                 newY = yPos + 1;
>                 }
>
>
>         newX = (newX + worldXSize) % worldXSize;
>         newY = (newY + worldYSize) % worldYSize;
>         
>         // Check that no other prey is at the new site.
>
>         if ([world getObjectAtX: newX Y: newY] == nil) {
>                 [world putObject: nil atX: xPos Y: yPos];
>                 xPos = newX;
>                 yPos = newY;
>                 [world putObject: self atX: newX Y: newY];}
It appears to me that, right here, you need:
                 foodHere = [food getValueAtX: newY Y: newY];
In order to tell the agent what its food condition is at the new spot.


>                 //[food addFood: newFood X: xPos Y: yPos];}
>         
The following does not work because your agent is on the cell, so it 
never is nil, and the food level never gets updated.

I don't think you should be having the agents cause the world to update.
I think, instead, there should be a separate action, triggered from the 
Model, which causes each cell in the world to adjust its food level. 
That way all cells get updated however you want.


>         if ([world getObjectAtX: newX Y: newY] == nil) {
>                 foodHere = foodHere + extraFood;
>                 printf("The food here - prey/unoccupied %d \n",
> foodHere);
>                 scanf("%d", &pos);
>                 }
>                                 
>                 else
>                         {foodHere = amountLeft + extraFood;
>                         printf("The food here - prey/occupied %d \n",
> foodHere);
>                         scanf("%d", &pos);
>                         }
>                         
>                 [food putValue: foodHere atX: xPos Y: yPos];
> 	foodHere = [food getValueAtX: xPos Y: yPos];   
> 	printf("foodhere - prey %d \n", foodHere);
>
>         if ((foodHere) <= amountEaten) {
>                 printf("There is not enough food to be eaten \n");
>         }
> printf("prey 1 \n");
>                 scanf("%d", &pos);        
>
>         
>         return self;
> }


--
Paul E. Johnson                       email: address@hidden
Dept. of Political Science            http://lark.cc.ku.edu/~pauljohn
1541 Lilac Lane, Rm 504
University of Kansas                  Office: (785) 864-9086
Lawrence, Kansas 66044-3177           FAX: (785) 864-5700


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