# pgRouting Manual (3.3)

## Coloring - Family of functions

- Supported versions: Latest (3.3) 3.2

# Coloring - Family of functions

Proposed

Warning

Proposed functions for next mayor release.

- They are not officially in the current release.

- They will likely officially be part of the next mayor release:

  - The functions make use of ANY-INTEGER and ANY-NUMERICAL

  - Name might not change. (But still can)

  - Signature might not change. (But still can)

  - Functionality might not change. (But still can)

  - pgTap tests have being done. But might need more.

  - Documentation might need refinement.

- pgr_sequentialVertexColoring - Proposed - Vertex coloring algorithm using greedy approach.

Experimental

Warning

Possible server crash

- These functions might create a server crash

Warning

Experimental functions

- They are not officially of the current release.

- They likely will not be officially be part of the next release:

  - The functions might not make use of ANY-INTEGER and ANY-NUMERICAL

  - Name might change.

  - Signature might change.

  - Functionality might change.

  - pgTap tests might be missing.

  - Might need c/c++ coding.

  - May lack documentation.

  - Documentation if any might need to be rewritten.

  - Documentation examples might need to be automatically generated.

  - Might need a lot of feedback from the comunity.

  - Might depend on a proposed function of pgRouting

  - Might depend on a deprecated function of pgRouting

- pgr_bipartite -Experimental - Bipartite graph algorithm using a DFS-based coloring approach.

- pgr_edgeColoring - Experimental - Edge Coloring algorithm using Vizing’s theorem.

## Parameters

Parameter | Type | Description
--- | --- | ---
Edges SQL | `TEXT` | Inner query as described below.

## Inner query

Edges SQL

  an SQL query of an undirected graph, which should return a set of rows with the following columns:

Column | Type | Default | Description
--- | --- | --- | ---
id | `ANY-INTEGER` |  | Identifier of the edge.
source | `ANY-INTEGER` |  | Identifier of the first end point vertex of the edge.
target | `ANY-INTEGER` |  | Identifier of the second end point vertex of the edge.

cost

`ANY-NUMERICAL`

- When positive: edge (source, target) exist on the graph.

- When negative: edge (source, target) does not exist on the graph.

reverse_cost

`ANY-NUMERICAL`

-1

- When positive: edge (target, source) exist on the graph.

- When negative: edge (target, source) does not exist on the graph.

Where:

ANY-INTEGER

  SMALLINT, INTEGER, BIGINT

ANY-NUMERICAL

  SMALLINT, INTEGER, BIGINT, REAL, FLOAT

## Result Columns

Returns SET OF `(vertex_id, color_id)`

Column | Type | Description
--- | --- | ---
vertex_id | `BIGINT` | Identifier of the vertex.

color_id

`BIGINT`

Identifier of the color of the vertex.

- The minimum value of color is 1.

Returns SET OF `(edge_id, color_id)`

Column | Type | Description
--- | --- | ---
edge_id | `BIGINT` | Identifier of the edge.

color_id

`BIGINT`

Identifier of the color of the edge.

- The minimum value of color is 1.

## See Also

- Boost: Sequential Vertex Coloring algorithm documentation

- Wikipedia: Graph coloring

- Boost: is_bipartite algorithm documentation

- Wikipedia: bipartite graph

- Boost: Edge Coloring Algorithm documentation

- Wikipedia: Graph Coloring

Indices and tables

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