【数模】Matlab allcycles()函数的源代码(2021a之前版本没有）

Matlaballcycles()函数的源代码

在之前的这篇博文里用程序求出有向图的所有有向圈（有向环）并可视化中用到了一个allcycles函数，这个函数只有2021a才有，如果matlab版本不高就用不了这个函数，所以为了方便大家使用，我把allcycles的内置函数找到然后分享给大家。

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
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做一点点小说明

计算有向图中的所有周期

CYCLES = ALLCYCLES(G)计算有向图G中的所有周期

单元格数组，其中CYCLES{i}是一个数值节点id的向量(如果G

没有节点名称)或字符向量的单元格数组(如果G

节点名称)。 CYCLES中的每个周期都从最小的节点开始

索引。 如果G是无环的，那么CYCLES为空。 周期在

辞典编纂的秩序。

[CYCLES, EDGECYCLES] = ALLCYCLES(G)也返回一个单元格数组

EDGECYCLES，其中EDGECYCLES{i}包含循环上的边

周期{我}的G。

[… = ALLCYCLES(G, Name, Value)指定一个或多个附加值

使用名称-值对参数的选项。 可用选项有:

MaxNumCycles-一个指定最大数目的标量

输出的周期。

MaxCycleLength-一个指定最大周期的标量

输出中的周期长度。

MinCycleLength -一个指定最小周期的标量

输出中的周期长度。