rmedge

Remove edge from graph

Syntax

H = rmedge(G,s,t)

H = rmedge(G,idx)

Description

H = rmedge(G,s,t) removes the edges specified by the node pairs s and t from graph G. If there are multiple edges specified by s and t, then they are all removed.

H = rmedge(G,idx) specifies which edges to remove with edge indices idx. The edge indices are row numbers in the G.Edges table.

Examples

Remove Edges with Specified End Nodes

Create and plot a graph.

s = [1 1 1 2 2 3 3 4 5 5 6 7];
t = [2 4 5 3 6 4 7 8 6 8 7 8];
G = graph(s,t);
plot(G)

Remove several edges from the graph and plot the result.

G = rmedge(G,[1 2 3 4],[5 6 7 8]);
plot(G)

Remove Edge with Specified Index

Create a graph and view the edge list.

s = {'BOS' 'NYC' 'NYC' 'NYC' 'LAX'};
t = {'NYC' 'LAX' 'DEN' 'LAS' 'DCA'};
G = digraph(s,t);
G.Edges

ans=5×1 table
         EndNodes     
    __________________

    {'BOS'}    {'NYC'}
    {'NYC'}    {'LAX'}
    {'NYC'}    {'DEN'}
    {'NYC'}    {'LAS'}
    {'LAX'}    {'DCA'}

Remove the edge between nodes 'NYC' and 'DEN' using the edge index.

G = rmedge(G,3);
G.Edges

ans=4×1 table
         EndNodes     
    __________________

    {'BOS'}    {'NYC'}
    {'NYC'}    {'LAX'}
    {'NYC'}    {'LAS'}
    {'LAX'}    {'DCA'}

Remove Self-Loops

This example shows how to remove all of the self-loops from a graph. Self-loops are edges that connect a node to itself.

Create a graph that has two self-loops.

G = graph([1 1 1 2],[1 2 3 2]);
plot(G)

Use rmedge to remove all self-loops from the graph. Even though G has only two self-loops, this technique removes all self-loops from any directed or undirected graph.

G = rmedge(G, 1:numnodes(G), 1:numnodes(G));
plot(G)

Input Arguments

G — Input graph

graph object | digraph object

Input graph, specified as either a graph or digraph object. Use graph to create an undirected graph or digraph to create a directed graph.

Example: G = graph(1,2)

Example: G = digraph([1 2],[2 3])

s,t — Node pairs (as separate arguments)

node indices | node names

Node pairs, specified as separate arguments of node indices or node names. Similarly located elements in s and t specify the source and target nodes for edges in the graph.

This table shows the different ways to refer to one or more nodes either by their numeric node indices or by their node names.

Form	Single Node	Multiple Nodes
Node index	Scalar Example: 1	Vector Example: [1 2 3]
Node name	Character vector Example: 'A'	Cell array of character vectors Example: {'A' 'B' 'C'}
	String scalar Example: "A"	String array Example: ["A" "B" "C"]

Example: G = rmedge(G,1,2) removes the edge between node 1 and node 2 from graph G.

Example: G = rmedge(G,{'a' 'b'},{'d' 'c'}) removes two edges from graph G, the first of which is between node 'a' and node 'd'.

idx — Edge indices

scalar | vector

Edge indices, specified as a scalar or vector. The edge indices are nonnegative integers that are row numbers in the G.Edges table.

Example: G = rmedge(G,[1 3 5]) removes the first, third, and fifth edges (rows) from G.Edges.

Output Arguments

H — Output graph

graph object | digraph object

Output graph, returned as a graph or digraph object.

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

Usage notes and limitations:

• The node pairs s and t must be node indices of the input graph G. Node names are not supported.

• When you construct a graph or digraph object in MATLAB^® and pass it to a MEX function generated using MATLAB Coder™, you cannot remove edges from the graph object.

Thread-Based Environment
Run code in the background using MATLAB® backgroundPool or accelerate code with Parallel Computing Toolbox™ ThreadPool.

Version History

Introduced in R2015b