Generating matrix as follows

1 次查看（过去 30 天）
NeGM
NeGM 2021-5-13
编辑： NeGM 2021-5-25
Hi Everyone,
I'd like to create random adjacency matrices for networks in the following form (see image), as you can see I have 6 nodes (n = 6) and each node must have 2 connections (degree = 2) to two other nodes chosen randomly. So the sum of each row must equal 2(or whatever value "degree" is assigned). The matrix must be symmetric with zeros along the diagonal (properties of the adjacency matrix). I have written a code that generates random adjacency matrices but Imnot sure how to constraint the program such that each node has exaclty 2 random connections.
A = zeros(n,n); % Create initial matrix
for i = 1:n
for j = 1:n
if i==j
A(i,j)=0; % Zero values in the diagonal entries
else
A(i,j)=round(rand); % Choosing random 0 and 1 values
A(j,i)=A(i,j); % Make A matrix symmetric
end
end
end
Any help is greatly appreciated, Thank you!

请先登录，再回答此问题。

采纳的回答

David Hill
David Hill 2021-5-13
Graph has to be a polygon.
numNodes=6;
a=randperm(numNodes);
b=circshift(a,1);
g=graph(a,b);
plot(g);
m=full(adjacency(g));
  3 个评论
显示 1更早的评论
David Hill
David Hill 2021-5-13
编辑：David Hill 2021-5-13
Some combinations of nodes and degrees will not work.
while 1
numNodes=20;
degrees=3;
n=repelem(1:numNodes,degrees);
s=[];t=[];
flag=1;
while ~isempty(n)
N=unique(n);
a=sum(n==N(1));
b=nchoosek(N(2:end),a);
try
c=b(randi(length(b)),:);
catch
flag=0;
break;
end
s=[s,n(n==N(1))];
t=[t,c];
n=n(a+1:end);
for k=1:a
try
n(find(n==c(k),1))=[];
catch
flag=0;
break;
end
end
end
if flag
g=graph(s,t);
plot(g);
m=full(adjacency(g));
break;
end
end
NeGM
NeGM 2021-5-13
Hey David, Thank you it works pretty well!

请先登录，再进行评论。

更多回答（1 个）

Matt J
Matt J 2021-5-13
编辑：Matt J 2021-5-13
Ran in:
Perhaps as follows,
n=6;
T=nan(n,2);
map=isnan(T);
while any(map(:))
[i,~]=find(map,1);
if ~map(i,1)
exclude=[i,T(i,1)];
elseif ~map(i,2)
exclude=[i,T(i,2)];
else
exclude=i;
end
pool=setdiff(find(any(map,2)),exclude);
if isempty(pool)
T=nan(n,2); map=isnan(T); continue
end
p=numel(pool);
j=pool(randi(p));
if map(i,1),
T(i,1)=j;
map(i,1)=0;
else,
T(i,2)=j;
map(i,2)=0;
end
if map(j,1),
T(j,1)=i;
map(j,1)=0;
else,
T(j,2)=i;
map(j,2)=0;
end
end
s=[(1:n), (1:n)].';
t=[T(:,1); T(:,2)];
st=unique(sort([s,t],2),'rows');
G=graph(st(:,1),st(:,2));
degree(G)
ans = 6×1
2 2 2 2 2 2
  3 个评论
显示 1更早的评论

请先登录，再进行评论。

类别

在 Help Center 和 File Exchange 中查找有关 Networks 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by