EdgeWeightedGraphQ

Status: Stable

documented, exercised by the test suite and/or worked examples, with no known limitations recorded.

Description

EdgeWeightedGraphQ[g]

gives True if g carries edge weights (EdgeWeight).

Examples (5)

Every input below was run against the current Mathilda build and its output recorded.

Options (1)

In[1]:= {WeightedGraphQ[Graph[{1,2},{1<->2},EdgeWeight->{3}]], WeightedGraphQ[CycleGraph[3]], EdgeWeightedGraphQ[Graph[{1,2},{1<->2},EdgeWeight->{3}]], EdgeWeightedGraphQ[CycleGraph[3]], WeightedGraphQ[x]}
Out[1]= {True, False, True, False, False}

Applications (4)

One weighted undirected edge

In[2]:= EdgeWeightedGraphQ[Graph[{1 <-> 2}, EdgeWeight -> {2}]]
Out[2]= True

A weighted directed path

In[3]:= EdgeWeightedGraphQ[Graph[{1 -> 2, 2 -> 3}, EdgeWeight -> {3, 4}]]
Out[3]= True

No EdgeWeight, so False

In[4]:= EdgeWeightedGraphQ[CycleGraph[4]]
Out[4]= False

A non-graph argument is False

In[5]:= EdgeWeightedGraphQ[0]
Out[5]= False

Implementation notes

Algorithm. builtin_edge_weighted_graph_q is defined as a direct call to builtin_weighted_graph_q, so it answers True iff g is a valid graph carrying an EdgeWeight option list (graph_is_valid(g) && graph_edge_weight_list(g) != NULL). The two predicates are deliberately identical: Mathilda has no vertex weights, so "edge weighted" and "weighted" are the same property.

Data structures. Delegation means there is no separate state — graph_edge_weight_list returns a borrowed pointer to the EdgeWeight List inside the canonical Graph[List verts, List edges, opts...] tree, and graph_is_valid is the memoized validator, so the validity half is O(1) after the first query on a node.

Complexity / limits. O(1) apart from the first validation pass. Like WeightedGraphQ it tests only that an EdgeWeight list is present, not that the stored weights are numeric or non-negative. A non-graph argument gives False and never stays unevaluated.

• Protected. A non-graph argument gives False.

Attributes: Protected.

References

See also: WeightedGraphQ, EdgeWeight

• Source: src/graph/gops_preds.c
• Specification: docs/spec/builtins/graphs.md
• Tests: tests/test_graph_ops.c

Notes & additional examples

Notes

EdgeWeightedGraphQ[g] is True exactly when g carries an EdgeWeight option — the same test as WeightedGraphQ, since Mathilda associates weights only with edges. It checks for the presence of the weight list, not that the weights are numeric.

A graph built without EdgeWeight is unweighted (each edge's weight defaults to 1 in the accessors) and gives False, as does any non-graph argument.