filling regions of matrix

Question

Mohammad Golam Kibria 2011-6-26

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/10289-filling-regions-of-matrix

Hi have a matrix.

I =

   0     0     1
   0     1     0
   1     0     0
   0     0     0
   1     0     0
   0     1     0
   0     0     1

Here ones in the matrix has divided the matrix in 3 regions.Is it possible to have the following type of output:

I =

   2     2     1
   2     1     1
   1     1     1
   1     1     1
   1     1     1
   3     1     1
   3     3     1
Thanks

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Answer 1

Andrei Bobrov 2011-6-26

1
链接

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https://ww2.mathworks.cn/matlabcentral/answers/10289-filling-regions-of-matrix#answer_14188

Iout = bwlabel(~cumsum(I,2))+1

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Oleg Komarov 2011-6-27

great! +1

Mohammad Golam Kibria 2011-6-27

Thanks

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Answer 2

the cyclist 2011-6-26

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/10289-filling-regions-of-matrix#answer_14167

There might be more efficient ways, but this will get the job done. I hope I didn't just do your homework for you.

I = [0     0     0     1; ...
     0     0     1     0; ...
     0     1     0     0; ...
     1     0     0     0; ...
     0     1     0     0; ...
     0     0     1     0; ...
     0     0     0     1];
[M,N] = size(I);
J = I;
for nj = 1:N
      % Find the ones in this column. Algorithm OK even if there's only one of them.
      firstOne = find(I(:,nj),1,'first');
      lastOne  = find(I(:,nj),1,'last');
      J(1:firstOne-1,    nj) = 2;
      J(firstOne:lastOne,nj) = 1;
      J(lastOne+1:end,   nj) = 3;
end
J