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Thread: Data structures and Message passing between turtles
Data structures and Message passing between turtles
country flaguser name
United States		 2007-07-30 11:16:10 

  


  

    




  



    

            
Hi,



I have a breed of turtles, I want them to send a message to each other

to implement a sort of token ring (The token is to be a data structure

which expands over time). Any ideas how to do this data structure and

message passing.




Also, what kind of debugging can be done in NetLogo? Is it primarily

print or show- based or is there any tool available for debugging (aka

Watches/breakpoints etc.) 



Take care,




Muaz



    
  

    
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    Re:  Data structures and Message passing
between turtles
  


  

     country flaguser name
United States		
     2007-07-30 14:42:37
  


  

    

  


  

    




  



    

            
Hi, Muaz!




I would probably implement the token itself as a breed of turtle, too.

The content of the token would be in a -own'd variable. Also, any

other token information, such as the source, destination, etc, can be

-own'd by the token turtle.



The turtles that are passing the token will then require a variable to

refer to the token, such as "token".



Then, creating a token is a matter of creating a new token turtle,

then setting the token variable of the node to the newly created token

turtle. A helper reporter can be used to make this easy and clear.



Passing the token then becomes a matter of one node setting the token

variable of a another node to its own token variable, before setting

the variable to nobody:



This is only one approach--you may desire or require a different one,

such as having nodes never set each others variables, but rather,

addressing tokens to each other, then picking up tokens addressed for

themselves.



Example breed definitions:



breed [ tokens a-token ]

tokens-own [ data source destination ]



breed [ nodes a-node ]

nodes-own [ token ]



to pass-to [ #node ]

    ;; Procedure to pass the token to a given node.

    ;; ... this is run by a node,

    ;; ... passes token to the given node

    set [ token ] of #node token

    ;; ... clear own reference to the token

    set token nobody

end



reporter used to to create a token:



to-report new-token [ #data #destination ]

    ;; assumes this is always run by a node (or other turtle)

    let me nobody

    hatch-tokens 1

    [ set me self

      set source myself

      set destination #destination

      set data #data

    ]

    report me

end




usage of the reporter:



;; this is run by a node when it is ready to create a token

     set token new-token some-data some-destination




Hope this helps,



~~James


_________________________

http://www.turtlezero.com




On 7/30/07, Muaz Niazi < thhgttg%40gmail.com">thhgttggmail.com> wrote:

&gt; Hi,

>

> I have a breed of turtles, I want them to send a message to each other

&gt; to implement a sort of token ring (The token is to be a data structure

> which expands over time). Any ideas how to do this data structure and

> message passing.


>

>; Also, what kind of debugging can be done in NetLogo? Is it primarily

> print or show- based or is there any tool available for debugging (aka

>; Watches/breakpoints etc.) 

>

>

> Take care,

&gt;

> Muaz



    
  

    
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.


    


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    Re:  Data structures and Message passing
between turtles
  


  

     country flaguser name
United States		
     2007-07-31 10:30:10
  


  

    
On Jul 30, 2007, at 12:16 PM, Muaz Niazi wrote:

>  I have a breed of turtles, I want them to send a
message to each other
>  to implement a sort of token ring (The token is to be
a data structure
>  which expands over time). Any ideas how to do this
data structure and
>  message passing. ... <snip>

Mauz,
Here is a demo with some more ideas for doing "sort of
a token ring". 
Since only one node can have the token, I just made the
token data and 
who-has-the-token global variables. I purposely didn't use
link turtles 
for this demo, but of course that would be a great way to do
it too, 
and opens up more possibilities for your model (like using
the layout 
procedures). Paste the code below into the Procedures of a
new 3.1 
model and make setup and go buttons to see it work. HTH,

Jim
--------------
; Demo Token Ring -- NetLogo 3.1 syntax

globals
[ token-data  ; the data of the token
   token-holder  ; agent ref of node with token
]

breed [ nodes node ]  nodes-own [ from-node to-node ]

to setup
   clear-all
   set-default-shape nodes "circle"

   ; make a 7-node ring
   create-custom-nodes 7 [ set color white  jump 4 ]
   let ring sort nodes
   (foreach ring rotate ring [ connect ?1 ?2 ])

   ; initialize token-data and start token at random node
   set token-data []
   ask one-of nodes [ pass-token ]
end

to pass-token  ; node -  pass token to next node
   set color white
   set token-holder to-node
   set color-of token-holder red
end

to connect [ #node1 #node2 ]
   set to-node-of #node1 #node2
   set from-node-of #node2 #node1  ; (not used in demo)
end

to-report rotate [ #list ]  ; rotate list forward
   report sentence (but-first #list) (first #list)
end

to go  ;;; demo
   if length token-data > 20 [ stop ]
   every 1
   [ ask token-holder
     [ ;;; do stuff to token
       if random 23 = 0 [ set token-data fput self
token-data ]
       pass-token
     ]
   ]
end



  


  

    
  

  
  
   
     
    
 
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