From a matrix, Pick one element from each row and not from same column for all possibilities. Only for non zero elements.

1 Ansicht (letzte 30 Tage)
Hi, From a matrix, I would like to pick one element from each row and not from same column for all possibilities.
Only for non zero elements.
Example, from A = [1 2 0; 1 2 0; 0 0 3], I want to obtain (1 2 3 and 2 1 3).
Thank you

Akzeptierte Antwort

Puru Kathuria
Puru Kathuria am 22 Jul. 2020
Hi,
Your requirements are answered in a similar question mentioned in this link. Also, selecting set of elements from a matrix such that each element comes from distinct row and column can also be modeled as a Matching problem. (graph theory)

Weitere Antworten (1)

Bruno Luong
Bruno Luong am 23 Jul. 2020
Bearbeitet: Bruno Luong am 23 Jul. 2020
A dynamic programming for fun
function p = nzperm(A,c)
if nargin < 2
c = 1;
end
r = find(A(:,c));
if isempty(r)
p = [];
elseif c==size(A,2)
p = A(r,c); % p = r(:);
else
p = [];
for i=r.'
Ai = A;
Ai(i,:) = 0;
q = nzperm(Ai,c+1);
a = A(i,c); % a = i
q = [a+zeros(size(q,1),1) q];
p = [p; q]; %#ok
end
end
Result
>> A=rand(5); A = A.*(rand(size(A))>0.6)
A =
0 0.6468 0.7881 0.5598 0.8008
0.5607 0 0 0 0.8961
0 0 0 0.9394 0.5975
0 0.4756 0.1335 0 0
0 0.3625 0.0216 0 0.9437
>> nzperm(A)
ans =
0.5607 0.6468 0.1335 0.9394 0.9437
0.5607 0.4756 0.7881 0.9394 0.9437
0.5607 0.4756 0.0216 0.5598 0.5975
0.5607 0.4756 0.0216 0.9394 0.8008
0.5607 0.3625 0.1335 0.5598 0.5975
0.5607 0.3625 0.1335 0.9394 0.8008
Note: this code will be slow on large array, since MATLAB make copies of matrix at every step. This algorithm could be implemented without copy using C mex.
  5 Kommentare
MeMariah
MeMariah am 20 Sep. 2020
@Bruno, you are right. large array take long. Unfortunately, I keep getting error when I try to generate the C mex file. Am using this app for the first time. Are able to help? error points to the line with
for i= r.'
Thanks.

Melden Sie sich an, um zu kommentieren.

Kategorien

Mehr zu Characters and Strings finden Sie in Help Center und File Exchange

Community Treasure Hunt

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

Start Hunting!

Translated by