momepy.gamma¶

momepy.gamma(graph, radius=5, name='gamma', distance=None, verbose=True)[source]¶

Calculates connectivity gamma index for subgraph around each node if radius is set, or for whole graph, if radius=None. A subgraph is generated around each node within set radius. If distance=None, radius will define topological distance, otherwise it uses values in distance attribute.

\[\alpha=\frac{e}{3(v-2)}\]

where \(e\) is the number of edges in subgraph and \(v\) is the number of nodes in subgraph.

Adapted from [Dibble et al., 2017].

Parameters:¶

graph : networkx.Graph¶

A Graph representing a street network. Ideally generated from GeoDataFrame using momepy.gdf_to_nx().

radius : int | None, optional¶

Include all neighbors of distance <= radius from n. If None, calculate the metric for the entire graph.

name : str, optional¶

The calculated attribute name.

distance : str, optional¶

Use specified edge data key as distance. For example, setting distance=’weight’ will use the edge weight to measure the distance from the node n.

verbose : bool (default True)¶

If True, shows progress bars in loops and indication of steps.

Returns:¶

• netx (Graph) – A networkx.Graph object if radius is set.

• float – The gamma index for the graph if radius=None.

Examples

>>> network_graph = mm.gamma(network_graph, radius=3)