PoDiGG

POpulation DIstribution-based Gtfs Generator

A realistic public transport dataset generator, which is serialized as GTFS.

It is based on five sub-generators:

• Region: A geographical area of cells where each cells contains a population value.
• Stops: Tagging of cells with stop or no stop.
• Edges: Adding transport edges between stops.
• Routes: Routes over one or more edges.
• Connections: Instantiation of routes at times.

Install

This generator is a Node.js application that can be installed by running:

[sudo] npm install -g podigg

Usage

Command line

The easiest way to run the generator is using the command line tool:

podigg [output folder [path to a JSON config file]]

The default output folder is output_data.

This config file contains parameters for the generator, as explained below. Example of a config file:

{
    "seed": 1,
    "stops:stops": 100,
    "connections:connections": 3000
}

Alternatively, the generator can also be configured using environment variables, as explained below. In that case, the generator must be called as follows:

podigg-env [output folder]

From code

The generator can be included into your application as follows:

const PodiggGenerator = require('podigg');
new PodiggGenerator({
    "seed": 1,
    "stops:stops": 100,
    "connections:connections": 3000
}).generate('output_data');

Docker

Downloading and running the container from the Docker hub:

docker pull podigg/podigg
docker run --rm -it -v $(pwd)/docker-out:/output_data -e GTFS_GEN_SEED=100 podigg/podigg

Building and running the container from this repo:

git clone [email protected]:PoDiGG/podigg.git
cd podigg
docker build -t podigg .
docker run --rm -it -v $(pwd)/docker-out:/output_data -e GTFS_GEN_SEED=100 podigg

Parameters must be passed using environment variables.

Parameters

All parameters are scoped by their generator name in lower-case, except for the general parameters. For example, choosing a region's latitude offset is done with the parameter region:lat_offset.

When configuring parameters via environment variables, parameters should be defined with the prefix GTFS_GEN_, followed by the generator name + __ (or empty if general) and the parameter name. The generator and parameter names can either be upper or lower case. For example, choosing a region's latitude offset is done with the parameter GTFS_GEN_REGION__LAT_OFFSET, and choosing the seed is done with GTFS_GEN_SEED.

General

| Name | Default Value | Description | | ------------- |-------------- | ------------- | | seed | 1 | The random seed |

Region

Several region generators exist which are explained hereafter, one of them needs to be selected.

Config prefix: region:

| Name | Default Value | Description | | ---------------- |-------------- | ------------- | | region_generator | isolated | Name of a region generator. (isolated, noisy or region) | | lat_offset | 0 | The value to add with all generated latitudes | | lon_offset | 0 | The value to add with all generated longitudes | | cells_per_latlon | 100 | The precision of the cells, how many cells go in 1 latitude or 1 longitude. |

File

| Name | Default Value | Description | | ---------------- |-------------- | ------------- | | region_file_path | null | Path to the cells in csv, this can also be a filename of an internal region file from the data directory, for example region_BE.csv. Expected columns (x:integer, y:integer, lat:float, long:float, density:float) |

Noisy

A noise-based generator, where population values are influenced by nearby cells.

| Name | Default Value | Description | | ------------- |-------------- | ------------- | | size_x | 300 | The width of the region in number of cells | | size_y | 300 | The height of the region in number of cells | | pop_average | 0 | The average population value for a cell | | pop_deviation | 10 | The standard deviation of the population value for a cell |

Isolated

A generator that creates a given number of circular clusters of population. The population density is high at the center of the cluster and decreases to zero when going to the border of the cluster.

| Name | Default Value | Description | | ------------- |-------------- | ------------- | | size_x | 300 | The width of the region in number of cells | | size_y | 300 | The height of the region in number of cells | | pop_average | 0 | The average population value for a cell | | pop_deviation | 10 | The standard deviation of the population value for a cell | | pop_clusters | 50 | The number of clusters to generate. | | max_radius | 50 | The maximum cluster radius. |

Stops

The generation of stops

Config prefix: stops:

| Name | Default Value | Description | | ----------------------------- |-------------- | ------------- | | stops | 600 | How many stops should be generated | | min_station_size | 0.01 | The minimum population value in a cell for a station to form | | max_station_size | 30 | The maximum population value in a cell for a station to form | | start_stop_choice_power | 4 | The power for selecting cells with a large population value as stops | | min_interstop_distance | 1 | The minimum distance between stops in number of cells | | factor_stops_post_edges | 0.66 | The factor of stops that should be generated after edge generation | | edge_choice_power | 2 | The power for selecting longer edges to generate stops on | | stop_around_edge_choice_power | 4 | The power for selecting cells with a large population value around edges as stops | | stop_around_edge_radius | 2 | The radius in number of cells around an edge to select points from |

Edges

The generation of edges

Config prefix: edges:

| Name | Default Value | Description | | --------------------------------------------- |-------------- | ------------- | | max_intracluster_distance | 100 | The maximum distance stops in one cluster can have from each other | | max_intracluster_distance_growthfactor | 0.1 | The lower this value, the larger the chance that closer stops will be clustered first before further away stations | | post_cluster_max_intracluster_distancefactor | 1.5 | The larger the value, the larger the chance that a stop will be connected to more stops | | loosestations_neighbourcount | 3 | The number of neighbours around a loose station that should define its area | | loosestations_max_range_factor | 0.3 | The maximum range to check around a loose station relative to the total region size | | loosestations_max_iterations | 10 | The max number of iterations to try to connect one loose station | | loosestations_search_radius_factor | 0.5 | The number to multiply with the loose station neighbourhood size to get the search radius for each step |

Routes

The generation of trips and routes

Config prefix: routes:

| Name | Default Value | Description | | -------------------------- |-------------- | ------------- | | routes | 1000 | The number of routes to generate | | largest_stations_fraction | 0.05 | The fraction of (largest) stops between which routes need to be formed | | penalize_station_size_area | 10 | The area in which stop sizes should be penalized | | max_route_length | 10 | The maximum number of edges a route can have in the macro-step, the larger, the slower this generator | | min_route_length | 4 | The minimum number of edges a route must have in the macro-step |

Connections

The generation of connections

Config prefix: connections:

| Name | Default Value | Description | | ----------------------------------|---------------------------------------------------------------------------------------------------------------------------- | ------------- | | time_initial | 0 | The initial timestamp (ms) of trip starting times | | time_final | 24 * 3600000 | The final timestamp (ms) of trip starting times | | connections | 30000 | The number of connections to generate | | stop_wait_min | 60000 | The minimum waiting time per stop in milliseconds | | stop_wait_size_factor | 60000 | The factor in milliseconds of stop waiting time to add depending on the station size | | route_choice_power | 2 | The power for selecting longer routes for instantiating connections | | vehicle_max_speed | 160 | The maximum speed of a vehicle in km/h, used to calculate the duration of a connection | | vehicle_speedup | 1000 | The vehicle speedup in km/(h^2), used to calculate the duration of a connection | | hourly_weekday_distribution | [0.05,0.01,0.01,0.48,2.46,5.64,7.13,6.23,5.44,5.43,5.41,5.49,5.42,5.41,5.57,6.70,6.96,6.21,5.40,4.95,4.33,3.31,1.56,0.42] | The chance (percentage) for each hour to have a connection on a weekday | | hourly_weekend_distribution | [0.09,0.01,0.01,0.08,0.98,3.56,5.23,5.79,5.82,5.89,5.84,5.91,5.88,5.95,5.87,5.95,5.89,5.96,5.92,5.94,5.62,4.61,2.45,0.76] | The chance (percentage) for each hour to have a connection on a weekend day | | delay_chance | 0 | The 0-1 chance that a connection will have a delay, 0 will not produce any delays (default) | | delay_max | 3600000 | The maximum delay in milliseconds | | delay_choice_power | 1 | Higher values means higher chance on larger delays | | delay_reasons | { 'td:DamagedVehicle': 0.4, 'td:Strike': 0.2, 'td:Accident': 0.2, 'td:BadWeather': 0.1, 'td:Obstruction': 0.1} | Default reasons for having delays with their respective chance. Keys must be prefixed with td: http://purl.org/td/transportdisruption# | | delay_reduction_duration_fraction | 0.1 | The maximum fraction of connection duration that can be subtracted when there is a delay |

Query Set

Optionally, PoDiGG can also generate realistic route planning query sets based on the generated dataset. For this, the queryset:generate option must be set to true.

Config prefix: queryset:

| Name | Default Value | Description | | --------------------------- |---------------------------------------------------------------------------------------------------------------------------- | ------------- | | start_stop_choice_power | 4 | Higher values means higher chance on larger stations when selecting starting stations | | query_count | 100 | The number of queries that should be generated | | time_initial | 0 | The initial timestamp (ms) | | time_final | 24 * 3600000 | The final timestamp (ms) | | max_time_before_departure | 3600000 | The maximum time in ms that a query for a certain departure time must be queried | | hourly_weekday_distribution | [0.05,0.01,0.01,0.48,2.46,5.64,7.13,6.23,5.44,5.43,5.41,5.49,5.42,5.41,5.57,6.70,6.96,6.21,5.40,4.95,4.33,3.31,1.56,0.42] | The chance (percentage) for each hour to have a connection on a weekday | | hourly_weekend_distribution | [0.09,0.01,0.01,0.08,0.98,3.56,5.23,5.79,5.82,5.89,5.84,5.91,5.88,5.95,5.87,5.95,5.89,5.96,5.92,5.94,5.62,4.61,2.45,0.76] | The chance (percentage) for each hour to have a connection on a weekend day |

License

The PoDiGG generator is written by Ruben Taelman.

This code is copyrighted by Ghent University – imec and released under the MIT license.