UrbanToyGraph

Toy graph to play with network metrics and algorithms mimicking typical urban patterns. The actual templates that can be modified by removing edges (and isolated nodes) are:

• Grid graph: A grid of m columns and n nodes. Can select a different width and height.
• Bridge graph: Two grids connected by a smaller number of edges.
• Radial graph: Roads coming from a central node in a star-shaped structure. Can select the number of radial roads that will be evenly distributed around the central node.
• Concentric graph: Nodes that are on connected circles. Can choose the number of radial roads and of circles (called zones). Can choose to put a central node connected to the first circle.
• Fractal graph: Roads coming from a central node and branching in a fractal way. Can select the number of branches and the level of fractality desired.

Installation

First clone the repository in the folder of your choosing:

git clone https://github.com/csebastiao/UrbanToyGraph.git

Locate yourself within the cloned folder, and create a new virtual environment. You can either create a new virtual environment then install the necessary dependencies with pip using the requirements.txt file:

pip install -r requirements.txt

Or create a new environment with the dependencies with conda or mamba using the environment.yml file:

mamba env create -f environment.yml

Once your environment is ready, you can locally install the package using:

pip install -e .

Functionalities

Create customizable spatial graph

Using the functions located in utg/create_graph, you can create spatial graphs, with non-intersecting edges having a geometry attribute. All graph can be created without additional arguments, but can be customized. Graph can be made osmnx-compatible using utg.utils.make_osmnx_compatible.

Graph templates

Here are some examples of graph made using create_graph functions. The plots are made and saved using utg.utils.plot_graph. The graph are saved in .graphml format using utg.utils.save_graph. All are made in the script scripts/graph_constructor.py. Since we have a geometry attribute, graph saved need to be loaded using utg.utils.load_graph, to transform WKT-string to shapely geometry. All graph files and their picture are located in the template-graph folder:

• Barcelona
• Bridge large
• Concentric large
• Fractaler cross

Add or remove edges

To add some noise in those perfectly geometrical graph you can use utg.create_graph.add_random_edges and utg.create_graph.remove_random_edges. These functions should work for any spatial graph having x and y attributes on every nodes.

⚠️ Be careful, utg.create_graph.add_random_edges is still WIP. It should not add forbidden edges if every edges are straight. For a concentric graph, use utg.create_graph.create_concentric_graph(straight_edges=True) to ensure straight edges. Even with straight edges, some edges that should be possible to add might not be added, because this function is based on Voronoi cells to find visible neighbors to connect to, limiting the choices to the closest neighbors.