Meld/Merge

Every StenoGraph starts out as a a vector of Edges. Key part of building a graph from this vector is homogenize the nodes and edges from this vector. This homogenization is driven by the two functions meld and merge:

StenoGraphs.meld — Function

meld(x)

Meldes a vector of edge/node. That means it tries to merge elements of the vector that relate to the same nodes.

Example

# `StenoGraphs` does not implement any `EdgeModifier`s
struct Weight{N <: Number} <: EdgeModifier w::N end;
e1 = Edge(Node(:a), Node(:b));
e2 = e1 * Weight(1.0);
e3 = UndirectedEdge(Node(:a), Node(:c));
e4 = UndirectedEdge(Node(:c), Node(:a));
es = [e1, e1, e2, e2, e3, e3, e4, e4]
meld(es) == [e2, e3]

# output

true

source

Base.merge — Function

merge(x, y)

Merges two (or more) edge/node and fails if not mergable. In contrast to meld, it returns always one edge/node or fails. Works for:

* ModifiedEdge
* ModifyingNode
* ModifiedNode
* DirectedEdge
* UndirectedEdge
* some combinations thereof (those that are mergable)

Requires carefull implementation by subtypes. Will unlikely work as expected out of the box for other subtypes because it is unclear what is mergable.

Example

# `StenoGraphs` does not implement any `EdgeModifier`s
julia> struct Weight{N <: Number} <: EdgeModifier w::N end

julia> merge(Edge(Node(:a), Node(:b)), Edge(Node(:a), Node(:b) * Weight(2)))
a → b * Weight{Int64}(2)

source