Synthetic Population

[mostaanh]

Dear MATSim Team,

I am new to MATSim and would like to ask is there a specific method that you use for population synthesis? or, do you have any suggestions on how I should do this?
Is there any any tutorial -except MATSim user guide and preferably video- in which you do a project from the first step?

Thanks

[Janekdererste]

Creating the population for MATSim is considered to be an upstream problem, so the project itself does not really provide any support to create populations. That said, this is a problem everyone faces when using MATSim, so I'll try to collect the resources that might be relevant:

• The most recent discussion I participated in is Issue #1173
• Dominik Ziemke has written an entire PhD-thesis on this topic.
• The Open Berlin Scenario has a custom population generation pipeline, which @rakow has used recently. The previous version has a corresponding publication, but I don't know whether this is still up-to-date.
• For France, we have the Equasim project, which also has an accompanying publication
• Issue #669 is also related to population creation. Mostly it is about how to use this example to generate a population from a commuter statistic.
• Issue #948 points to equasim as well.
• Issue #796 clears some technical details about populations
• Issue #279 also includes references to synthetic population generation in Sun & Erath (2015) or Joubert (2018)

[mostaanh]

Let's consider I have all the information which is needed to build the Population/Plan file -I synthesis population and they all have daily plan-, how can I generate MATSim Population File?

There are some links at page 69 in the MATSim user guide but they are not working.

Thanks

[Janekdererste]

I tried to create a minimal example of how to create a population as a separate comment so that it can be upvoted. Please let me know whether this helps.

[Janekdererste]

We have examples for creating a population here. To make these examples executable, they contain code which is additional to the actual code that shows the population API. Below, I tried to only include the part which deals with the API to generate a population, as a minimal example.

        // Let's assume that this is your orignal data. You need to read in this data somehow.
        // Let's also assume, that your data is a list of persons and each person has a list of
        // activities. I used Object here, as I don't know what type of data you have
        List<List<Object>> originalData = new ArrayList<>();

        // create an empty population
        var population = PopulationUtils.createPopulation(ConfigUtils.createConfig());

        // all data containers in MATSim use the factory patter. New data items are created by a factory, which is
        // associated with the data container.
        var factory = population.getFactory();

        // loop over all the persons from the orignal data
        for (var person: originalData) {

            // each person needs a unique id which you must generate from your original data
            // you could also just assign each person a number, if that's better.
            var personId = "";
            var matsimPerson = factory.createPerson(Id.createPersonId(personId));
            var matsimPlan = factory.createPlan();

            // iterate over the person's activities which is the inner list in this example
            // The plan consists of activity, leg, activity, leg, activity. The following loop adds
            // these items in this order. It is important to add activities and legs in alternating
            // order
            for (var activity : person) {

                // the activity coordinate must come from your data. (0,0) is just the placeholder here
                var coord = new Coord(0, 0);
                // the activity type must come from your data. "home" is just a placeholder here
                var activityType = "home";
                var matsimActivity = factory.createActivityFromCoord(activityType, coord);

                // the activity starts at 1 in the morning. This should come from your data
                matsimActivity.setStartTime(3600);
                // the activity lasts 2 hours. This should come from your data
                matsimActivity.setMaximumDuration(2 * 3600);
                // one can also set an end time. We need two of the three times declared to locate the
                // activity temporally. One of the three can stay undefined. 
                matsimActivity.setEndTime(3*3600);

                matsimPlan.addActivity(matsimActivity);

                // the leg mode must come from your data, or, if you don't know the distribution of modes,
                // you can let everyone start with walk and then synthetic persons will choose other modes
                // during the calibration of your model
                var legMode = "walk";
                var matsimLeg = factory.createLeg(legMode);
                matsimPlan.addLeg(matsimLeg);
            }

            // the last item in the plan is a leg at the moment. Therefore we add one more activity
            // the activity coordinate must come from your data. (0,0) is just the placeholder here
            var coord = new Coord(0, 0);
            // the activity type must come from your data. "home" is just a placeholder here
            var activityType = "home";
            var matsimActivity = factory.createActivityFromCoord(activityType, coord);
            matsimPlan.addActivity(matsimActivity);

            // the plan is done, we can assign the plan to the person
            matsimPerson.addPlan(matsimPlan);
            // the person has a plan now. We can add it to the population container
            population.addPerson(matsimPerson);
        }

        // we have copied the original data into MATSim's synthetic population. As a last step we can write it into
        // a file, so that it can be used by the simulation
        PopulationUtils.writePopulation(population, "/path/to/your/population.xml.gz");