kruskal_mst and prim_mst return different types from SimpleWeightedGraph input #17
Description
The kruskal_mst function may contain some logic that the prim_mst function lacks. When I supply a SimpleWeightedGraph as input, the kruskal_mst function returns a vector of SimpleWeightedEdge. By contrast, the prim_mst function returns a vector of SimpleEdge instead. The behavior of kruskal_mst seems more beneficial, to me. Here is a small example:
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| | |_| | | | (_| | | Version 1.7.1 (2021-12-22)
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julia> using Graphs, SimpleWeightedGraphs
julia> A=[0 7 0 5 0 0 0;0 0 8 0 7 0 0;0 0 0 0 5 0 0;0 0 0 0 18 6 0;0 0 0 0 0 8 9; 0 0 0 0 0 0 11;0 0 0 0 0 0 0]
7×7 Matrix{Int64}:
0 7 0 5 0 0 0
0 0 8 0 7 0 0
0 0 0 0 5 0 0
0 0 0 0 18 6 0
0 0 0 0 0 8 9
0 0 0 0 0 0 11
0 0 0 0 0 0 0
julia> kruskal_mst(SimpleWeightedGraph(A + A'))
6-element Vector{SimpleWeightedEdge{Int64, Int64}}:
Edge 1 => 4 with weight 5
Edge 3 => 5 with weight 5
Edge 4 => 6 with weight 6
Edge 1 => 2 with weight 7
Edge 2 => 5 with weight 7
Edge 5 => 7 with weight 9
julia> prim_mst(SimpleWeightedGraph(A + A'))
6-element Vector{Graphs.SimpleGraphs.SimpleEdge{Int64}}:
Edge 1 => 2
Edge 5 => 3
Edge 1 => 4
Edge 2 => 5
Edge 4 => 6
Edge 5 => 7