predecessors

Node predecessors

Syntax

preIDs = predecessors(G,nodeID)

Description

preIDs = predecessors(G,nodeID) returns the predecessor nodes of the node in directed graph G specified by nodeID. The predecessor nodes form directed edges with preIDs as the source nodes, and nodeID as the target node.

Examples

Node Predecessors

Create and plot a directed graph and determine the predecessor nodes of node 'e'.

s = [1 1 1 2 2 3 3 7 8];
t = [2 3 4 5 6 7 8 5 5];
names = {'a' 'b' 'c' 'd' 'e' 'f' 'g' 'h'};
G = digraph(s,t,[],names);
plot(G)

preIDs = predecessors(G,'e')

preIDs = 3x1 cell
    {'b'}
    {'g'}
    {'h'}

Input Arguments

G — Input graph

digraph object

Input graph, specified as a digraph object. Use digraph to create a directed graph object.

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

nodeID — Node identifier

node index | node name

Node identifier, specified as one of the values in this table.

Value	Example
Scalar node index	1
Character vector node name	'A'
String scalar node name	"A"

Example: preIDs = predecessors(G,3) finds the predecessor nodes of node 3.

Output Arguments

preIDs — Predecessor node IDs

node indices | node names

Predecessor node IDs, returned as a node indices or node names.

• If nodeID is a numeric node index, then preIDs contains numeric node indices.

• If nodeID is a node name, then preIDs contains node names.

Tips

• For multigraphs with multiple edges between the same two nodes, the output of inedges can be longer than that of predecessors, since there can be multiple incoming edges from some of the predecessors.

Extended Capabilities

C/C++ Code Generation

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

Usage notes and limitations:

• The node identifier nodeID must be a numeric node index of the input graph G. Node name is not supported.

Version History

Introduced in R2015b