[digital analog] source code of MATLAB allcycles() function (not available before 2021a)

Matlaballcycles() Function source code

In this previous blog post Use a program to find all the directed cycles of a directed graph （ Directed ring ） And visualize There's one used in allcycles function , This function has only 2021a Only then , If matlab If the version is not high, you can't use this function , So for the convenience of everyone , I put allcycles Find the built-in function of and share it with you .

function [cycles, edgecycles] = allcycles(G, varargin)
% ALLCYCLES Compute all cycles in digraph
%   CYCLES = ALLCYCLES(G) computes all the cycles in digraph G. CYCLES is a
%   cell array in which CYCLES{
    i} is a vector of numeric node IDs (if G
%   does not have node names) or a cell array of character vectors (if G
%   has node names). Each cycle in CYCLES begins with the smallest node
%   index. If G is acyclic, then CYCLES is empty. The cycles are in
%   lexicographical order.
%
%   [CYCLES, EDGECYCLES] = ALLCYCLES(G) also returns a cell array
%   EDGECYCLES in which EDGECYCLES{
    i} contains the edges on the cycle
%   CYCLES{
    i} of G.
%
%   [...] = ALLCYCLES(G, Name, Value) specifies one or more additional
%   options using name-value pair arguments. The available options are:
%
%         'MaxNumCycles' - A scalar that specifies the maximum number
%                          of cycles in the output.
%       'MaxCycleLength' - A scalar that specifies the maximum cycle
%                          length of cycles in the output.
%       'MinCycleLength' - A scalar that specifies the minimum cycle
%                          length of cycles in the output.
%
%   See also ISDAG, HASCYCLES, CYCLEBASIS, ALLPATHS

%   Copyright 2020-2021 The MathWorks, Inc.
%
%   Reference:
%   Johnson, Donald B. "Finding all the elementary circuits of a directed
%   graph." SIAM Journal on Computing 4.1 (1975): 77-84.

[maxNumCycles, maxCycleLength, minCycleLength] = parseInputs(varargin{
    :});

if maxCycleLength < minCycleLength
    cycles = cell(0, 1);
    edgecycles = cell(0, 1);
    return
end

try
    if nargout < 2
        cycles = allSimpleCycles(G.Underlying, maxNumCycles, maxCycleLength,...
            minCycleLength);
    else
        [cycles, edgecycles] = allSimpleCycles(G.Underlying, maxNumCycles,...
            maxCycleLength, minCycleLength);
    end
catch e
    if e.identifier == "MATLAB:nomem"
        error(message('MATLAB:graphfun:allcycles:nomem'));
    else
        rethrow(e);
    end
end

[names, hasNodeNames] = getNodeNames(G);
names = names.';
if hasNodeNames
    for i = 1:size(cycles, 1)
        cycles{
    i} = names(cycles{
    i});
    end
end
end

function [maxNumCycles, maxCycleLength, minCycleLength] = parseInputs(varargin)
names = {
    'MaxNumCycles', 'MaxCycleLength', 'MinCycleLength'};
maxNumCycles = Inf;
maxCycleLength = Inf;
minCycleLength = 1;
for i = 1:2:numel(varargin)
    opt = validatestring(varargin{
    i}, names);
    if i+1 > numel(varargin)
        error(message('MATLAB:graphfun:allcycles:KeyWithoutValue', opt));
    end
    switch opt
        case 'MaxNumCycles'
            maxNumCycles = varargin{
    i+1};
            validateattributes(maxNumCycles, {
    'numeric'}, {
    'scalar', 'real', 'nonnegative', 'integer'}, '', 'MaxNumCycles')
        case 'MaxCycleLength'
            maxCycleLength = varargin{
    i+1};
            validateattributes(maxCycleLength, {
    'numeric'}, {
    'scalar', 'real', 'positive', 'integer'}, '', 'MaxCycleLength')
        case 'MinCycleLength'
            minCycleLength = varargin{
    i+1};
            validateattributes(minCycleLength, {
    'numeric'}, {
    'scalar', 'real', 'positive', 'integer'}, '', 'MinCycleLength')
    end
end
end

Do a little novel Ming

Calculate all periods in a directed graph

CYCLES = ALLCYCLES(G) Computing digraphs G All cycles in

Cell array , among CYCLES{ i} Is a numerical node id Vector ( If G

No node name ) Or a cell array of character vectors ( If G

The name of the node ). CYCLES Every cycle in starts with the smallest node

Indexes . If G It's acyclic , that CYCLES It's empty . The cycle is

The order of lexicography .

[CYCLES, EDGECYCLES] = ALLCYCLES(G) Also returns an array of cells

EDGECYCLES, among EDGECYCLES{ i} Include the edges on the loop

cycle { I } Of G.

[… = ALLCYCLES(G, Name, Value) Specify one or more additional values

Use the name - Value to parameter options . The available options are :

MaxNumCycles- A scalar that specifies the maximum number

Period of output .

MaxCycleLength- A scalar that specifies the maximum period

Cycle length in output .

MinCycleLength - A scalar that specifies the minimum period

Cycle length in output .