focals

dgm.algorithm.focals allows for finding focal sources and sinks in a graph.

Example usage

To obtain the source and sink nodes as well as a heatmap

from opendgm.algorithm.focals import AreaFlows, NodeSources

graph = ... # opendgm Graph object

flows = (
    AreaFlows(graph)
    .set_radius(16)
    .run()
)

sources_and_sinks, heatmap = (
    NodeSources(*flows)
    .set_threshold(0.8)
    .run()
)

AreaFlows

Bases: NodeFlows

radius = 10 instance-attribute

__init__(graph)

filter_area_paths(node_source, area_nodes)

Filter area nodes that have no in-area connection to the source node. i.e. all area nodes for which the source node has no connection into said area node are removed.

Parameters:

Name	Type	Description	Default
node_source	int	the graph nodes for which we want to filter connections	required
area_nodes	ndarray	all nodes within its area	required

Returns:

Type	Description
ndarray	np.ndarray: filtered area nodes

run()

Calculate the in-, out- and contained degree of each node to an area within radius.

Returns:

Type	Description
tuple[ndarray, ndarray, ndarray]	tuple[np.ndarray]: in-, out- and contained degree

set_radius(radius)

NodeFlows

Bases: NKAlgorithm

The In other words, the in- and out- degree for each node.

run()

Calculates the in- and out flow for each node in the graph.

Returns:

Type	Description
tuple[ndarray, ndarray]	tuple[np.ndarray, np.ndarray]: in and out degree for each node.

NodeSources

Calculate normalized in/out flow balance and determine if each node is a source or a sink.

contained_flows = contained_flows instance-attribute

in_flows = in_flows instance-attribute

out_flows = out_flows instance-attribute

__init__(in_flows, out_flows, contained_flows)

run(min_edges=2)

Calculate normalized in/out flow balance and determine if each node is a source or a sink.

Source nodes are labeled as 1, sink nodes are labeled as -1. If the balance falls within the range [-threshold, threshold], the nodes are neither sources nor sinks and labeled as 0.

Returns:

Type	Description
ndarray	np.ndarray: nodes heatmap of normalized in/out flow balance