I am trying to create a netlogo program in which turtles move around randomly and create links with each other when they cross the same patch. I would like to implement the average path length of the network after a certain number of ticks.
I have got as far as the turtles creating links but am unsure how to implement an average minimum path length. How would I go about implementing this and showing it on a monitor?
Look at the networks extension and, in particular, the nw:mean-path-length primitive. Calculating mean path length is computationally expensive, don't write your own procedure.
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Im currently building a Anylogic model and want to calculate average time spent by customer in different flow paths (I have added the process flow below). In the picture i have named the paths i want to calculate the average time as path A and path B
Anyligic has dedicated blocks for this (although it can be done simply in code).
See in detail here.
The TimeMeasureEnd block contains a dataset.
The following code returns the average of the Y-axis values:
timeMeasureEnd.dataset.getYMean();
Good luck!
I am using the PedGoTo block in Anylogic pedestrian library to direct pedestrians to the nearest exit (TargetLine). But since there are walls between pedestrians and exits, I can't just calculate straight line distance. In PedGoTo Anylogic official reference guide, it says
In Reach target mode the path is automatically calculated by the library.
I wonder if there's a function to calculate this path like path = getPath(ped, targetLine), and I can get the distance of this route, like path.getDistance()?
Afaik there is no such method. The reason is that the Ped library constantly re-evaluates the path taken and adjusts it based on new conditions.
So if you want to compute the nearest exits, you have to do it manually. Easiest would be to use paths, as Jaco-Ben suggested.
However: This may not actually be a good idea, depending on your actual scenario. In reality, people also do NOT know the nearest exit, typically (unless it is trivial).
PS: Also check the example model on fire exit behavior
I don't think there is an API for the pedestrian library similar to what you have with the GIS map.
You can however record the distance as the pedestrian is traveling - and once you have these distances you can perhaps use them in a future scenario? You will need to manually record all the distances in a separate run and then store the values to be used in a next run.
Here is a simple examplke in case it helps you.
What I would do then is to run this for a number of locations that pedestrians will be at when they need to choose an exit. Store the final distance in a separate txt file with a starting location as the key... and then in the next run of your simulation, you use these distances as an approximation of the distance to the exits and let the pedestrain then decide where to go to based on their current location and shortest distance to the exist...
So for every agent, you find the nearest point you have a distance to exists for and then use that, plus the distance to the exists
This seems like a lot of work... but for now I don't see any other way. Would love to see if anyone gets a better solution!
I would like to know whether is it possible in NetLogo to set the random-seed according to the number of repetitions in the Behavior Space.
I know there is the command random-seed behaviorspace-run-number, but it sets a different seed for every run of the model. This is not what I want because I am trying to explore the impact of a variation in the values of a parameter on a specific random network structure. By using random-seed behaviorspace-run-number I get a different network structure for each value of the parameter within the same repetition of the experiment, which is not what I want.
Can anyone help me on this?
Thanks a lot,
Emanuele
There's not a variable that gives you exactly what you want, but BehaviorSpace runs through the parameter sets in a specific order. Say you have 5 repetitions of 20 parameter combinations, so there's 100 runs. It will do the first run of 20 combinations, then the second series etc. So you can do some mathematics or some if/then to go from the behaviorspace-run-number to the random-seed (eg floor behaviorspace-run-number / 20 if you want it to change every 20 runs).
Sorry for long post. I am newbie in agent-based modelling. So please accept my apology in advance if my question sounds stupid. I am trying to model a scenario where framer (i.e. agent) decides which type of crop should be harvest in different types of fields to increase the profit. The farmer agent has a budget i.e. the amount of money that can be spent on farming each time step equal to $100.
The farmer operates a farm that is subdivided into nine fields, which are arranged in a 3x3
cellular grid. Each field is of the same size. Water availability varies spatially across the fields with a rating of either 1 (driest), 2 (moderate),
or 3 (wettest). The manner in which water availability varies across the fields (i.e. randomly).
The farmer must choose among three crops. As initial parameter settings, the crops have the
following characteristics:
Yield Price Costs Minimum Water Req.
Crop 1 300 20 15 3
Crop 2 200 12 10 2
Crop 3 100 7 5 1
Each crop requires a certain amount of water to grow. Crop yields will only be realized if the crop is
planted in a field with at least the crop’s minimum water requirement.
Now the problem is that I couldn't find any function in Netlogo that calculates the permutation or combination of crop, field, and water requirements to calculate the expected profit. Any help would be high appreciated.
I believe you describe a linear programming problem.
Useful functions for solving Simplex Linear Programming problems are in NumAnal extension, which does not come bundled with NetLogo but which you can get as follows:
In NetLogo, under Tools / Extensions ... you can find NumAnal, probably with no green check-mark. Select it. On the right, you have buttons to install it, and then one to add it to your code. When you click those, it should now get a green checkmark and you should have a new line in your code "extensions [ numanal ]", and you are now able to use those commands, with the "numanal:" prefix, for example, numanal:simplex.
The documentation for it is in the folder where it was installed. But where is that?
Sadly, the documentation for where extensions are downloaded is not current.
https://ccl.northwestern.edu/netlogo/docs/extensions.html#where-extensions-are-located
After exhaustive search by date-modified, I actually found the folder on my Windows 10 laptop here: c:\Users\condor\AppData\Roaming\NetLogo\6.1\extensions
( Note the "\Roaming\" ).
That folder has a README.md text file, and a pdf document named "NumAnal-v3.4.0" explaining how to use it, and an examples folder with code. It is a little dense.
Here's a link to the basics of how to describe a Linear Programming problem, which is beyond the scope of StackOverflow. You can find help via Google.
Here's one 8 minute video ( as of 24-Nov-2019) that might help you figure out if this is what you need.
Simplex Algorithm Explanation (How to Solve a Linear Program)
https://www.youtube.com/watch?v=RO5477EKlXE
I have a NetLogo model, simplified to this:
to setup
clear-all
create-turtles 1000 [
fd 100
]
end
When I add a monitor widget to the UI, with a reporter like mean [xcor] of turtles and then run setup, the values in the monitor change a slight bit constantly. It might show 0.2305090322262271 one moment then 0.2305090322262268 the next, and then another similar number on and on.
What is making my monitor widget flicker or flash like this? How can I prevent it?
This is caused by a combination of a few things:
NetLogo's use of floating point numbers, which can produce small accuracy issues. See Floating point accuracy in the NetLogo programming guide: https://ccl.northwestern.edu/netlogo/docs/programming.html#math
Agentsets such as turtles are always returned in a random order.
Monitors re-run their reporter calculation constantly, even when you are not running any model code with a forever button or through the command center.
So the monitor constantly re-runs its mean [xcor] of turtles reporter, but the turtles agentset gives the turtles in a random order, and so the floating-point inaccuracies for mean will accumulate in a slightly different way each time due to the order differences. The end result is you see very slightly different numbers flashing through the monitor widget while nothing is happening.
You would see the same problem doing sum [xcor] of turtles or variance [xcor] of turtles - anytime you're reducing a bunch of floating point numbers from an agentset into a single value. You can also see the problem running your reporter code directly in the command center repeatedly, without a monitor widget at all.
The fixes are fortunately pretty easy:
Sort your numbers before you calculate: mean sort [xcor] of turtles, sum sort [xcor] of turtles, variance sort [xcor] of turtles. If the numbers are in the same order you'll still have small floating-point inaccuracies, but they'll be the the same every time so you won't see the values change. This is probably the best solution, but it can be slow if you have a really large agentset.
Change the Decimal places setting of your monitors to a number where you don't notice the changing values. Since the differences in results should be small, this is usually possible.