Hi,
I am planning to simulate the anti predator behaviour of a species and
wonder if Netlogo is a suitable environment. I need to simulate group
cohesion, co-operative hunting etc and, as I do not have a great deal
of programming experience, would appreciate any advice.

Thanks

Jim

Hi to everyone,
my problem is how to define the distance between each patch of a
certain type (e.g. URBAN-PATCHES) to the nearest patch of a different
type (e.g. COMMERCIAL-PATCHES).
Obviously I need a procedure that takes each patch and searches for the
minimum distance, but which exactly could that be?

Thanks in advance for helping me out...

Have you seen the existing predator-prey models in the 'Models Library'
in NetLogo? (e.g. open NetLogo and presss ctrl-m to go to the models
library).

Through the web you can find other predator-prey NL models e.g.:
Googling "predator prey netlogo" gives:

http://academic.evergreen.edu/m/mcavityd/NetLogo.htm

I am also a newbie to NL programming but I am managing to learn the
language through looking at the NL dictionary and programming guides,
looking at how other models are coded, and the support through this list
is really useful.

Howard

lang.jim61 wrote:
> Hi,
> I am planning to simulate the anti predator behaviour of a species and
> wonder if Netlogo is a suitable environment. I need to simulate group
> cohesion, co-operative hunting etc and, as I do not have a great deal
> of programming experience, would appreciate any advice.
>
> Thanks
>
> Jim
>
>
>

Can NetLogo be used as a plain, basic, classic, generic Logo?

I want to start working with NetLogo with just a bare-bones screen,
with one turtle and a command prompt.  I am not interested in NetLogo
models just yet, but some NetLogo features, particularly the Java Sound
interface.

Something like this:


min-one-of AGENTSET [ distance myself ]

For example, assuming that patches-own [ nearest-commercial ], you
could do this:

ask urban-patches
[ set nearest-commercial min-one-of commercial-patches [ distance myself ]
]


"distance myself" means "the distance between this patch, and the
patch that is making me run this code"

In this case, it is each urban patch, in turn,  making the commercial
patches run the code "distance myself".  So, "myself" refers back to
the urban patch.

Hope this helps~

~~James





On Mon, Jun 2, 2008 at 11:15 AM, auth1lag <no_reply@yahoogroups.com> wrote:
> Hi to everyone,
> my problem is how to define the distance between each patch of a
> certain type (e.g. URBAN-PATCHES) to the nearest patch of a different
> type (e.g. COMMERCIAL-PATCHES).
> Obviously I need a procedure that takes each patch and searches for the
> minimum distance, but which exactly could that be?
>
> Thanks in advance for helping me out...

Hi,

I would like to perform a loop in Netlogo model.
I want to change a variable's value with step 1,2,3,4... every time
and every time the first variable reach number 12 a second variable
start from number 1, then when the first variable reach the value 24
the second variable to be set to value 24 etc.

How can I create such a loop in Netlogo?

Thanks in advance

Michael

I can't answer your specific problem because I am not entirely sure
what you want to do with 'who' but he's a little bit of a messy tip.
If you put this into google:

filetype:nlogo who

you'll find lots of nlogo programs with examples of using who.
hopefully one of them will be close to what you want.

regards, howard

--- In netlogo-users@yahoogroups.com, Manuel M <mnl_moreira@...> wrote:
>
> Hi colleagues,
>
> I am pretty new in netlogo's world, I wonder if you can help me with
a simple question.
>
> How can I ask a turtle to inform me about his ID?
>
> I know how to use the who function to select a particular turtle but
I do not know how to ask the turtle to give me ID.
>
> The dictionary says: "
>         You can use the turtle reporter to retrieve a turtle with a
given
>         who number" but I cannot find out how to do it from the code
>
> Thanks in advance,
>
> Manuel
>
>
>
> __________________________________________________
> Correo Yahoo!
> Espacio para todos tus mensajes, antivirus y antispam ¡gratis!
> ¡Abrí tu cuenta ya! - http://correo.yahoo.com.ar
>

Hello Dear Netlogo Users

I am new netlogo user and currently trying to model bargaining power
of farmers and traders at farmgate transaction. I have got a
difficulty of intering spesific variables to each type of agents? Is
that the same if inspect each agent and fill the data manually? and
then start defining each variables in the procedure tab? waiting your
response and even an excellent idea.

Sincerly,

Thank you very much for the advice.

JIm

--- In netlogo-users@yahoogroups.com, "lang.jim61" <lang.jim61@...>
wrote:
>
> Hi,
> I am planning to simulate the anti predator behaviour of a species
and
> wonder if Netlogo is a suitable environment. I need to simulate group
> cohesion, co-operative hunting etc and, as I do not have a great deal
> of programming experience, would appreciate any advice.
>
> Thanks
>
> Jim
>

>
> I am pretty new in netlogo's world, I wonder if you can help me with a simple
question.
>
> How can I ask a turtle to inform me about his ID?
>
> I know how to use the who function to select a particular turtle but I do not
know how to ask the turtle to give me ID.
>
> The dictionary says: "
>        You can use the turtle reporter to retrieve a turtle with a given
>        who number" but I cannot find out how to do it from the code
>

Hi Manuel -

You should probably take a look at the variables section of the
programming guide:

http://ccl.northwestern.edu/netlogo/docs/programming.html#variables

turtles can access their own variables directly, for example.

ask turtles[ print who ]

will print the who numbers of all the turtles to the command center.

the observer can access turtle variables using OF, for example:

print [who] of turtle 0

will print '0' to the command center.

hope this helps.

esther

Oh, right.
You can use the OTHER operator to exclude an agent itself from an
agentset... so we'd do that in the first part:
(capitalized for emphasis, only. Netlogo code is case-insensitive)
;; simply find an unused computer (that is not this computer)
let free-computer one-of OTHER computers with [ not is-person? user ]
;; is there a free computer?
if is-computer? free-computer
[ ;; use this computer
set using free-computer
;; logon to the computer
;; (tell the free computer that I am using it)
ask free-computer [ set user myself ]
]
Another way to write the "one-of other... " line would be this:
one-of computers with [ not is-person? user and self != myself ]
SELF and MYSELF are concepts that give some users trouble, but are
very useful to understand.
Please keep asking questions!
~~James
On Thu, May 29, 2008 at 11:35 AM, Howard Noble
<howard.noble@...> wrote:

Thanks James.
This is a lot more than I bargained for with my question so I'll try
battle through all the concepts I don't understand yet.
You've given me loads of new ideas too e.g. allow the simulation user to
create two types of simulation: one heterogeneous based on mean
parameters, and one homogeneous, based on a single individual. I'll call
the second version "if everyone was like me" ...the world will fall apart!
One quick question. I want to use the linking version to tie agents
together (because it is easiest way to show the relationship in the
View). The code you sent through throws an error because the computers
try to link to themselves eventually. How can I stop this? I tried
something like:
...
if (is-computer? free-computer) and (is-computer? free-computer not self)
[ create-usage-with free-computer ]
...
but this is grammatically wrong. I can't work out how to write this
correctly.
H

Hi Jim,

next to the predator-prey and wolf-sheep examples, there are some
flocking examples that will improve your flock cohesion. I'm not sure
for an example on cooperative hunting, but Netlogo would be the ideal
place to start true agent-based simulations on this! (you'll have to
figure out the algoritms there by yourself.)

Geerten

hi,dear friends:
   i need build the Third-Party logistics model in supply chain network,
Do anyfriend know the model of Third-Party logistics ??

Hello,

I've got what I want to achieve in one part of my program working but
the code is very clunky and needs speeding up.

Can anyone suggest some coding approaches or general ideas as to how I
can improve this code. It seems that hatching causes things to slow down
dramatically (despite the number of agents being small):

(What I am trying to do is create a 'realistic' simulation that will
predict actual monetary and CO2 emissions through computer usage within
an organisation. this is toy code so  i can make events happen (not
currently triggering any events) according to the time of day, week,
year, and run the simulation over a specific time (hard coded here).

The .nlogo file is here:
http://modelling4all.wikidot.com/local--files/temp-howard/calculating-time4June2\
008a.nlogo

Thanks, howard

globals [
is-working-day?
hour-in-day
hour-in-week
current-day
week
year
total-recycled
]

turtles-own [ age ]

to setup
ca
crt 2
ask turtles [
fd random 10
set age random 8
set color blue
]
set hour-in-week 0
set is-working-day? "true"
set total-recycled 0
set hour-in-day 0
set current-day "monday"
set week 0
set year 0
end

to go
calculate-is-working-day?
increment-time
ask turtles [
   get-older
   purchase
   recycle
]
tick
if ticks >= (24 * 365 * 10) [
stop
]
end

to increment-time
set hour-in-week (hour-in-week + 1)
work-out-hour-in-day
work-out-day
end

to work-out-hour-in-day
set hour-in-day (hour-in-day + 1)
if hour-in-day = 24 [
set hour-in-day 0
]
end

to work-out-day
if hour-in-week <= 24 [
set current-day "monday"
]
if hour-in-week > 24 and hour-in-week < 2 * 24 [
set current-day "tuesday"
]
if hour-in-week > 2 * 24 and hour-in-week < 3 * 24 [
set current-day "wednesday"
]
if hour-in-week > 3 * 24 and hour-in-week < 4 * 24 [
set current-day "thursday"
]
if hour-in-week > 4 * 24 and hour-in-week < 5 * 24 [
set current-day "friday"
]
if hour-in-week > 5 * 24 and hour-in-week < 6 * 24 [
set current-day "saturday"
]
if hour-in-week > 6 * 24 and hour-in-week < 7 * 24 [
set current-day "sunday"
]
end

to calculate-is-working-day?
ifelse hour-in-week <= (5 * 24) [
set is-working-day? "true"
]
[
set is-working-day? "false"
]
if hour-in-week >= (7 * 24)  [
update-weeks
set hour-in-week 0
]
end

to update-weeks
set week week + 1 ;; count the number of weeks that have passed
if week = 52 [
update-years
set week 0
]
end

to update-years
set year year + 1
end

to get-older
set age age + 1 ;; this is by 1 hour
end

to purchase
if age > 24 * 365 * 2 [ ;; purchase after 2 years
hatch 1 [
set age 0
set color red
fd 3
]
]
end

to recycle
if age > 24 * 365 * 3 [ ; make computer die if older than 3 years
set total-recycled total-recycled + 1
die
]
end

I am trying to simulate a group of players playing the ultimatum
bargaining game, with a selection process in which players pair up,
with the more successful player reproducing and the less successful
player being eliminated. I am having trouble pairing up players in
NetLogo: it is simple to have a player select a random opponent, but
I want this opponent, as well as the acting player, to be removed
from the competition pool until the next turn.

The following is the code that I am currently using:

   ask turtles [

   set competed? 0
   set birth? 0

   let opponent one-of other turtles
   let opponent2 one-of other turtles with [competed? = 0]

   ifelse random 2  = 0 ;; "coin-flip"

   [if offer >= [bottom-line] of opponent [set money money + 100 -
offer]]

   [if bottom-line <= [offer] of opponent [set money money + [offer]
of opponent]]

   set money money - 25 - .25 * money

   if opponent2 != nobody
   [
   if money = [money] of opponent2
   [set competed? 1 set [competed?] of opponent2 1]
   if money > [money] of opponent2
   [set birth? 1 set competed? 1 set [kill?] of opponent2 1 set
[competed?] of opponent2 1]
   if money < [money] of opponent2
   [set kill? 1 set competed? 1 set [birth?] of opponent2 1 set
[competed?] of opponent2 1]
   ]

   ]

   ask turtles with [kill? = 1] [die]
   ask turtles with [birth? = 1] [hatch 1 [forward random 5 right
random 360 set money 0]]


With this code, players find a random opponent. If they have equal
money to the opponent, both survive. If one player has more money,
that player hatches and the other dies after all turtles have played.

I would expect this program to keep the population constant. However,
when I run it, the population decreases on the first turn, then is
maintained for the remainder of the game.

Any help on this would be greatly appreciated. I would be happy to
forward the entire file to someone if it would be helpful.

Hi -

On Tue, 3 Jun 2008, getachew wrote:

> Hello Dear Netlogo Users
>
> I am new netlogo user and currently trying to model bargaining power
> of farmers and traders at farmgate transaction. I have got a
> difficulty of intering spesific variables to each type of agents? Is
> that the same if inspect each agent and fill the data manually? and
> then start defining each variables in the procedure tab? waiting your
> response and even an excellent idea.
>

I don't understand what you want to do.

are you asking if typing variables in the fields in the agent monitors is
the same as typing "set variable value" in the procedures or command
center?  If so the answer is yes.

You want to set turtle variables to specific values, do you have that data
in a file?  do you want read data from a file?  See the File I/O section
of the programming guide:

http://ccl.northwestern.edu/netlogo/docs/programming.html#fileio

If I've missed the point of your question please try rephrasing it.

thanks

esther

Hi Michael -

On Tue, 3 Jun 2008, mxanthakis wrote:

> I would like to perform a loop in Netlogo model.
> I want to change a variable's value with step 1,2,3,4... every time
> and every time the first variable reach number 12 a second variable
> start from number 1, then when the first variable reach the value 24
> the second variable to be set to value 24 etc.
>
> How can I create such a loop in Netlogo?
>

I'm not sure I understand what you want. There is a WHILE operator in
NetLogo.  You can probably do what you are asking with that and some
local variables. However, if you explain to me more generally what you
want to do I might be able to be more helpful.  Usually there's a way in
NetLogo to avoid using direct loops like that.

good luck.

esther

The order that procedure and reporter definitions appear in the
procedure pane does not affect the order you can use them in GO or
other procedures.

In a procedure, commands execute in the order they appear, one after the other.

If it is important that ALL turtles complete ONE procedure before any
turtles begin the NEXT procedure, use seperate ask clauses:

ask turtles [ do-procedure-one ]
ask turtles [ do-procedure-two ]

If it is important that each turtle complete all the commands before
ANY other turtle starts running any commands, then put the commands
inside a single ASK:

ask turtles
[ do-procedure-one
   do-procedure-two
   do-procedure-three
]

I hope this helps.

On Wed, Jun 4, 2008 at 11:30 AM, Daniel Tanis <daniel.tanis@...> wrote:
> Hello,
> I need some help to establish the order in which my simulation procedures
> are been made.
> I have a GO command that asks turtles to do a sequence of procedures and
> than a sequence of Report commands that calculate the sum of all turtles
> values that have been calculated by the GO commands.
> My problem is that I would like to use the first two reporters for my the
> last five procedures in GO command.
> How do I do that and how do I know what is calculated first and second and
> third and so on ?
>
> Regards
> Daniel Tanis

>>>>> "jelaly" == jelaly  <younesje@...> writes:

  jelaly> I am trying to simulate a group of players playing the
  jelaly> ultimatum bargaining game, with a selection process in which
  jelaly> players pair up, with the more successful player reproducing
  jelaly> and the less successful player being eliminated. I am having
  jelaly> trouble pairing up players in NetLogo: it is simple to have a
  jelaly> player select a random opponent, but I want this opponent, as
  jelaly> well as the acting player, to be removed from the competition
  jelaly> pool until the next turn.

  jelaly> The following is the code that I am currently using:

  jelaly>   ask turtles [

  jelaly>   set competed? 0 set birth? 0

  jelaly>   let opponent one-of other turtles let opponent2 one-of other
  jelaly> turtles with [competed? = 0]

I'm not sure if this is the cause of your bug (or the only cause), but I
think you probably meant to use multiple ASK commands, like this:

   ask turtles [ set competed? 0 ]
   ask turtles [ let opponent ... ]

so that all of the turtles set their competed? variable to 0 before any
turtle chooses an opponent.

Also, while it will work fine to use 0 to mean false and 1 to mean true,
it's more idiomatic NetLogo to use the boolean true and false values
directly:

   ask turtles [ set competed? false ]

then instead of writing:

   ask turtles with [birth? = 1]

you can just write:

   ask turtles with [birth?]

--
Seth Tisue / http://tisue.net
lead developer, NetLogo: http://ccl.northwestern.edu/netlogo/

>>>>> "Howard" == Howard Noble <howard.noble@...> writes:

  Howard> Can anyone suggest some coding approaches or general ideas as
  Howard> to how I can improve this code. It seems that hatching causes
  Howard> things to slow down dramatically (despite the number of agents
  Howard> being small):

If I run your model for even just a few seconds, I end up with several
thousand turtles.  I only see a few turtles in the view, but that's
because most of the turtles are stacked up on top of each other.
Perhaps that's your bug?  I'd suggest adding a monitor to the model that
shows "count turtles", so you can keep an eye on the agent count.

Also, try changing the view update mode from "continuous" to
"tick-based" and pushing the speed slider all the way over towards
"faster".  In the default position, the view gets updated once per tick.
You're going through a lot of ticks very quickly, so NetLogo is spending
a lot of its time updating the view.  Pushing the speed slider to the
right will decrease the frequency of view updates.  (We don't recommend
using the "continuous" setting for normal modeling purposes.  It's
usually only useful if you're just messing with code and don't want to
bother using the tick counter.)

--
Seth Tisue / http://tisue.net
lead developer, NetLogo: http://ccl.northwestern.edu/netlogo/

>>>>> "Howard" == Howard Noble <howard.noble@...> writes:

  Howard> line 13: then I
  Howard> don't understand how this line works, i don't understand how
  Howard> you can ask *free-computer* anything as its not an agent but a
  Howard> procedure variable.

free-computer is a variable which contains an agent.  so if you write:

   ask free-computer [ ... ]

you're asking the agent stored in the variable to do something.

  Howard> generally i see that *user-id *is being set
  Howard> to the who number of the agent that is calling it e.g. in this
  Howard> case user-id is being set to the who number of the computer
  Howard> that is running this procedure.

Not the who number.  The agent itself.  Who numbers aren't used in this
code at all.  (That's standard NetLogo style.  Usually you don't need to
use who numbers at all, unless you're doing something unusual.)

Hope this helps,

--
Seth Tisue / http://tisue.net
lead developer, NetLogo: http://ccl.northwestern.edu/netlogo/

>>>>> "cplusplus" == cplusplus guru <cplusplus_guru@...> writes:

  cplusplus> Can NetLogo be used as a plain, basic, classic, generic
  cplusplus> Logo?  I want to start working with NetLogo with just a
  cplusplus> bare-bones screen, with one turtle and a command prompt.  I
  cplusplus> am not interested in NetLogo models just yet, but some
  cplusplus> NetLogo features, particularly the Java Sound interface.

If you only want one turtle you can create one using "crt 1" or "cro 1".
(The former will give you a turtle with a random color and heading; the
latter always results in a gray turtle facing north.)  Then you can
change the command center from "observer>" to "turtles>" (using the
popup menu, or just press the Tab key) and issue turtle commands.

http://ccl.northwestern.edu/netlogo/docs/faq.html#logodiffs has a
discussion of language differences between plain Logo and NetLogo.

--
Seth Tisue / http://tisue.net
lead developer, NetLogo: http://ccl.northwestern.edu/netlogo/