How to perform row wise operation for a matrix of 350x350

Hi, I have a matrix of 350x350 all zeros and ones. Now i have to go through each row and assign 40 to all 1s in the first line until i hit a 0, then i have to go to the second row and assign 40 to all 1s until i hit zero and i have to repeat this until the n-th line is 0 and i have to continue the same concept for the remaining numbers i.e now i have to again start with first row but this time from the place where i have left it last time i.e. the number(1) after zero should replace with some random number other than 40 and i have to continue the same concept for 350x350 matrix

for example if A=[1 0 1 0 1; 1 0 1 0 1;1 0 0 0 0; 0 0 0 1 1;1 1 0 0 0] it should change to A=[40 0 50 0 60; 40 0 50 0 60; 40 0 0 0 0 ;0 0 0 70 70; 80 80 0 0 0];

From the code below i could be able to change the values for initial rows but i have no idea how to proceed further so, can anyone help me with this and the code below is only working if the row starts with 1 but i have some rows where it is starting with 0s (if the row is starting with 0 it should be neglected)

for i = 1:size(A, 1) 
      ind = find(A(i, :) == 0); 
      if isempty(ind)
        ind2 = size(A, 2);
      else
        ind2 = ind(1) - 1;
      end
      A(i, 1:ind2) = 40; 
    End

Thanks in advance Agastya

[Image Analyst]

Reference (original question): http://www.mathworks.com/matlabcentral/answers/163722-how-to-perform-row-wise-operation-for-a-matrix-of-250x250

Answer 1

[Guillaume]

The following would work:

for row = 1:size(A, 1)
   pos0 = [0 find([A(row, :) 0] == 0]; %make sure that beginning and end are included
   for idx = 1:numel(pos0)-1
      A(row, pos0(idx)+1 : pos0(idx+1)-1) = 30 + 10*idx;
   end
end

[Agastya]

Hi Guillaume,

No its not working, i am getting error\ posidx?

[Guillaume]

Well, you could have worked out the fix yourself.

Anyway, I've edited the post to fix the two typos.

The idea of the code is to fill the row from (index of zero + 1) to (index of next zero - 1) with the appropriate value.

[Agastya]

Hi Guillaume,

Thank you very much

Answer 2

[Matt J]

Insert

    if ~A(i,1), continue; end