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Diffstat (limited to '.venv/lib/python3.12/site-packages/networkx/exception.py')
-rw-r--r-- | .venv/lib/python3.12/site-packages/networkx/exception.py | 131 |
1 files changed, 131 insertions, 0 deletions
diff --git a/.venv/lib/python3.12/site-packages/networkx/exception.py b/.venv/lib/python3.12/site-packages/networkx/exception.py new file mode 100644 index 00000000..c960cf13 --- /dev/null +++ b/.venv/lib/python3.12/site-packages/networkx/exception.py @@ -0,0 +1,131 @@ +""" +********** +Exceptions +********** + +Base exceptions and errors for NetworkX. +""" + +__all__ = [ + "HasACycle", + "NodeNotFound", + "PowerIterationFailedConvergence", + "ExceededMaxIterations", + "AmbiguousSolution", + "NetworkXAlgorithmError", + "NetworkXException", + "NetworkXError", + "NetworkXNoCycle", + "NetworkXNoPath", + "NetworkXNotImplemented", + "NetworkXPointlessConcept", + "NetworkXUnbounded", + "NetworkXUnfeasible", +] + + +class NetworkXException(Exception): + """Base class for exceptions in NetworkX.""" + + +class NetworkXError(NetworkXException): + """Exception for a serious error in NetworkX""" + + +class NetworkXPointlessConcept(NetworkXException): + """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 with ``n`` nodes + and 0 edges, and a ``null_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 NetworkXAlgorithmError(NetworkXException): + """Exception for unexpected termination of algorithms.""" + + +class NetworkXUnfeasible(NetworkXAlgorithmError): + """Exception raised by algorithms trying to solve a problem + instance that has no feasible solution.""" + + +class NetworkXNoPath(NetworkXUnfeasible): + """Exception for algorithms that should return a path when running + on graphs where such a path does not exist.""" + + +class NetworkXNoCycle(NetworkXUnfeasible): + """Exception for algorithms that should return a cycle when running + on graphs where such a cycle does not exist.""" + + +class HasACycle(NetworkXException): + """Raised if a graph has a cycle when an algorithm expects that it + will have no cycles. + + """ + + +class NetworkXUnbounded(NetworkXAlgorithmError): + """Exception raised by algorithms trying to solve a maximization + or a minimization problem instance that is unbounded.""" + + +class NetworkXNotImplemented(NetworkXException): + """Exception raised by algorithms not implemented for a type of graph.""" + + +class NodeNotFound(NetworkXException): + """Exception raised if requested node is not present in the graph""" + + +class AmbiguousSolution(NetworkXException): + """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. + + """ + + +class ExceededMaxIterations(NetworkXException): + """Raised if a loop iterates too many times without breaking. + + This may occur, for example, in an algorithm that computes + progressively better approximations to a value but exceeds an + iteration bound specified by the user. + + """ + + +class PowerIterationFailedConvergence(ExceededMaxIterations): + """Raised when the power iteration method fails to converge within a + specified iteration limit. + + `num_iterations` is the number of iterations that have been + completed when this exception was raised. + + """ + + def __init__(self, num_iterations, *args, **kw): + msg = f"power iteration failed to converge within {num_iterations} iterations" + exception_message = msg + superinit = super().__init__ + superinit(self, exception_message, *args, **kw) |