Exceptions#
Base exceptions and errors for NetworkX.
- class NetworkXPointlessConcept[source]#
Raised when a null graph is provided as input to an algorithm that cannot use it.
The null graph is sometimes considered a pointless concept [1], thus the name of the exception.
Notes
Null graphs and empty graphs are often used interchangeably but they are well defined in NetworkX. An
empty_graph
is a graph withn
nodes and 0 edges, and anull_graph
is a graph with 0 nodes and 0 edges.References
[1]Harary, F. and Read, R. “Is the Null Graph a Pointless Concept?” In Graphs and Combinatorics Conference, George Washington University. New York: Springer-Verlag, 1973.
- class NetworkXUnfeasible[source]#
Exception raised by algorithms trying to solve a problem instance that has no feasible solution.
- class NetworkXNoPath[source]#
Exception for algorithms that should return a path when running on graphs where such a path does not exist.
- class NetworkXNoCycle[source]#
Exception for algorithms that should return a cycle when running on graphs where such a cycle does not exist.
- class HasACycle[source]#
Raised if a graph has a cycle when an algorithm expects that it will have no cycles.
- class NetworkXUnbounded[source]#
Exception raised by algorithms trying to solve a maximization or a minimization problem instance that is unbounded.
- class NetworkXNotImplemented[source]#
Exception raised by algorithms not implemented for a type of graph.
- class AmbiguousSolution[source]#
Raised if more than one valid solution exists for an intermediary step of an algorithm.
In the face of ambiguity, refuse the temptation to guess. This may occur, for example, when trying to determine the bipartite node sets in a disconnected bipartite graph when computing bipartite matchings.