GRAPHS

A graph is a collection of nodes and edges

let graph = new Graph()

This creates an empty graph with no nodes or edges

Graphs don't exist in 2D space (or any space), they are an abstract map showing connections between nodes.

The graph holds onto all its nodes and edges in arrays.
The types are Graph Node and Graph Edge.

graph.nodes = []  // array of GraphNode
graph.edges = []  // array of GraphEdge

This operation makes a new node and returns a reference to it.

let node = graph.newNode()  // node is a GraphNode

A new edge needs to know the 2 nodes its connecting.

let edge = graph.newEdge(node1, node2)  // edge is a GraphEdge

You can always grab a node or an edge again

graph.newNode()
let node = graph.nodes[0]  // the first node

This graph is interactive

graph.nodes[].adjacentNodes()
graph.edges[].adjacentNodes()

Two nodes are adjacent if they are connected by an edge

An edge connects two nodes

graph.edges[0]  // the first edge
graph.edges.length  // total number of edges

graph.nodes[].adjacentEdges()
graph.edges[].adjacentEdges()

Invalid edges
Circular: an edge cannot connect the same node at both ends
Duplicate: the same 2 nodes cannot have more than 1 edge between them

graph.removeNode(node)

When removing a node, any edges which share the node will be removed also.

graph.removeEdge(edge)

Removing an edge will do simply that and the nodes remain untouched.

graph.clean()

Cleaning a graph removes duplicate and circular edges. You can also target specific edges:

graph.removeEdge(edge)
graph.removeEdgeBetween(node1, node2)

Removing Nodes:

graph.removeNode(node)
graph.removeIsolatedNodes()

Isolated nodes are nodes that aren't connected to an edge.

graph.mergeNodes(node1,node2)

Each of these functions returns a GraphClean Object

{
  edges:{total:number, duplicate:number, circular:number},
  nodes:{total:number, isolated:number}
}

Each of the entries in a GraphClean object is the number of elements of that type removed