Class: QgsGraph¶

Mathematical graph representation.

Methods

`addEdge`	Add an edge to the graph, going from the fromVertexIdx to toVertexIdx.
`addVertex`	Add a vertex to the graph
`edge`	Returns the edge at the given index.
`edgeCount`	Returns number of graph edges
`findOppositeEdge`	Finds the first edge which is the opposite of the edge with the specified index.
`findVertex`	Find vertex by associated point
`hasEdge`	Returns whether the edge of the given index exists.
`hasVertex`	Returns whether the vertex of the given index exists.
`removeEdge`	Removes the edge at specified index.
`removeVertex`	Removes the vertex at specified index.
`vertex`	Returns the vertex at the given index.
`vertexCount`	Returns number of graph vertices

class qgis.analysis.QgsGraph[source]¶

Bases: object

addEdge(self, fromVertexIdx: int, toVertexIdx: int, strategies: Iterable[Any]) → int[source]¶

Add an edge to the graph, going from the fromVertexIdx to toVertexIdx.

Parameters:

fromVertexIdx (int)
toVertexIdx (int)
strategies (Iterable[Any])

Return type:

int

addVertex(self, pt: QgsPointXY) → int[source]¶

Add a vertex to the graph

Parameters:: pt (QgsPointXY)
Return type:: int

edge(self, idx: int) → QgsGraphEdge[source]¶

Returns the edge at the given index.

Raises:: IndexError – if the edge is not found.
Parameters:: idx (int)
Return type:: QgsGraphEdge

edgeCount(self) → int[source]¶

Returns number of graph edges

Return type:: int

findOppositeEdge(self, index: int) → int[source]¶

Finds the first edge which is the opposite of the edge with the specified index.

This represents the edge which has the same vertices as the specified edge, but the opposite direction in the graph.(I.e. the edge which starts at the “from” vertex of the specified edge and ends at the “to” vertex.)

Returns -1 if no opposite edge exists.

Raises:: IndexError – if the edge with the specified index is not found.

Added in version 3.24.

Parameters:: index (int)
Return type:: int

findVertex(self, pt: QgsPointXY) → int[source]¶

Find vertex by associated point

Return type:: int
Returns:: vertex index
Parameters:: pt (QgsPointXY)

hasEdge(self, index: int) → bool[source]¶

Returns whether the edge of the given index exists.

Added in version 3.24.

Parameters:: index (int)
Return type:: bool

hasVertex(self, index: int) → bool[source]¶

Returns whether the vertex of the given index exists.

Added in version 3.24.

Parameters:: index (int)
Return type:: bool

removeEdge(self, index: int)[source]¶

Removes the edge at specified index.

The incoming and outgoing edges for all graph vertices will be updated accordingly. Vertices which no longer have any incoming or outgoing edges as a result will be removed from the graph automatically.

Raises:: IndexError – if the vertex is not found.

Added in version 3.24.

Parameters:: index (int)

removeVertex(self, index: int)[source]¶

Removes the vertex at specified index.

All edges which are incoming or outgoing edges for the vertex will also be removed.

Raises:: IndexError – if the vertex is not found.

Added in version 3.24.

Parameters:: index (int)

vertex(self, idx: int) → QgsGraphVertex[source]¶

Returns the vertex at the given index.

Raises:: IndexError – if the vertex is not found.
Parameters:: idx (int)
Return type:: QgsGraphVertex

vertexCount(self) → int[source]¶

Returns number of graph vertices

Return type:: int