This project is a simple example that illustrates how to generate a PNG image file that shows the shortest distances from a random/central node of a road network to all other nodes. Below you see an example of how this can look like. The darker the color, the closer it is to the starting node of the shortest path tree:

This example also shows how to use the networkx output of OsmToRoadGraph.

If you already have a *.json file you can move to How to run.

1. Download an OSM XML file (e.g., from here http://download.geofabrik.de/europe/germany.html you can download the [.osm.bz2] file)
2. Unzip the file to obtain the pure xml file (e.g., bremen-latest.osm)
3. Run OsmToRoadGraph by invoking python3 run.py -f <FILENAME> -n p -c --networkx (e.g., python3 run.py -f data/bremen-latest.osm -n p -c --networkx)
4. This should have created the *.json (e.g., data/bremen-latest.json)

1. Make sure you have a *.json file (if not, see the section above)
2. Install the dependencies: pip3 install -r requirements.txt
3. Invoke this script as follows:

python3 shortest-distances-drawing.py -f <INPUT_FILENAME> -o <OUTPUT_FILENAME>

For example:

python3 shortest-distances-drawing.py -f data/berlin-latest.json -o berlin.png

That's it: This should an output picture of the shortest distances of road network of the input OSM file.

This little script offers some more customization options:

Options:
  -h, --help            show this help message and exit
  -f IN_FILENAME, --file=IN_FILENAME
                        input networkx JSON file
  -o OUT_FILENAME, --out=OUT_FILENAME
                        output png file
  -c, --center          set this option to compute the shortest distances from
                        an approximate center node [default: random node]
  -m METRIC, --metric=METRIC
                        metric for the shortest path algorithm. Either
                        'length' or 'travel-time' [default: travel-time]
  --width=WIDTH         image width in px [default=1600]
  --height=HEIGHT       image height in px [default=1200]

If you want to run the code faster you can also use pypy3:

1. Get pypy3 https://www.pypy.org/index.html
2. Bootstrap pip pypy3 -m ensurepip
3. Install dependencies: pypy3 -m pip install -r requirements.txt
4. Run it pypy3 shortest-distances-drawing.py -f <INPUT_FILENAME> -o <OUTPUT_FILENAME>