combining matrix rows with repeated elements

3 次查看（过去 30 天）
Javad
Javad 2014-7-31
评论： Javad 2014-8-8
I have a matrix which its some rows have one same elements. I want to combine this rows and save the result in a cell array without repeating the elements. What is the easiest way to do so? For example, I have
A = [1 2;3 4;2 5;5 6;4 7;8 9;10 9]
And want to get,
C = {[1 2 5 6],[3 4 7],[8 9 10]}
  5 个评论
显示 3更早的评论
dpb
dpb 2014-7-31
Which is what I said...start w/ the unique values you have then look where they're located and build the array therefrom...
>> [u,ia,ib]=unique(A(:),'stable');
>> u'
ans =
1 3 2 5 4 8 10 6 7 9
>> ia'
ans =
1 2 3 4 5 6 7 11 12 13
>> ib'
ans =
1 2 3 4 5 6 7 3 5 4 8 9 10 10
>>
As you can see, you get the list of values and their locations which you can use to select which ones go where...I'll leave that as "exercise for the student"... :)
Javad
Javad 2014-8-8
Thanks for your point. I had a look at documentations which say u=A(ia) and A=u(ib), but I could not figure out how I can relate indices to separate them as I want. As a beginner, it's a little difficult for me to do this exercise!

请先登录，再进行评论。

请先登录，再回答此问题。

回答（1 个）

Jian Wei
Jian Wei 2014-7-31
If I understand it correctly, you are trying to cluster the vertices in a graph into different groups according to whether they are connected or not. For general cases, the problem might be nontrivial. Please try the following code to see if it generates the results you need.
% adjacency matrix
M = zeros(max(max(10)));
for k = 1:size(A,1)
M(A(k,1),A(k,2)) = 1;
M(A(k,2),A(k,1)) = 1;
end
flag = zeros(length(M),1);
C = cell(0);
for k = 1:length(M)
if flag(k)==0
p1 = k;
flag(k) = 1;
p2 = p1;
for ki = 1:length(p1)
node = p1(ki);
p2 = union(p2,find(M(node,:)==1));
end
while length(p2)~=length(p1)
p1 = p2;
p2 = p1;
for ki = 1:length(p1)
node = p1(ki);
p2 = union(p2,find(M(node,:)==1));
end
end
for ki = 1:length(p2)
flag(p2(ki)) = 1;
end
C{end+1} = p2;
end
end
C is the cell which contains different groups of vertices that are connected with each other.

类别

在 Help Center 和 File Exchange 中查找有关 Sparse Matrices 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