Can someone check my code ?

Question

Maria 2022-9-11

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https://ww2.mathworks.cn/matlabcentral/answers/1802900-can-someone-check-my-code

编辑： Maria 2022-9-16

采纳的回答： Torsten

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Hello!

I have a binary matrix A (m*n),in each row i want to keep arbitrary just '1' in order to get sum in each row ="1"

at first i selected the last non zero value in each row with this code :

[rows, columns] = size(A)
% Create an array to keep track of the column of the last 1 in each row.
lastNonZeroColumn = zeros(rows, 1);
% Loop over rows, finding the last 1 in each row.
for row = 1 : rows
    % Find the last 1 in this row, if any exist.
    col = find(A(row, :), 1, 'last');
    if ~isempty(col)
        % At least one 1 exists.  Log it's location.
        lastNonZeroColumn(row) = col;
    end
end
% Display results in command window:
lastNonZeroColumn

after this i picked out just '1' except the last non zero value, i used this code :

N=zeros(size(A);
for k=1:size(A,1)
    index=find(A(k,1:lastNonZeroColumn(i)-1));
    if isempty(index),continue;end
    select=randperm(length(index),1);
    N(k,index(select))=1;
end

but i still get '1' at the position of last non zero value.

can anyone help me please!

thanks in advance.

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Walter Roberson 2022-9-15

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(Not relevant to this question, but in order to get this message through to the poster who deleted a question earlier:)

With regards to the summation you asked about:

R in your equation appears to be a fixed value. You are adding the fixed value together T times,

R  %t = 1 to 1
R+R = 2*R  %t = 1 to 2
R+R+R = 3*R %t = 1 to 3

and so on.

And you are wanting to compare that matrix sum to the scalar value k.

if k is 0 then D = 0, since sum t=1:0 of something is 0 as no elements would be added
if k is > 0 and any R>0 then D = ceil(max(R(:))/k)
if k is negative then D = 0 since as we showed above the empty sum is 0 and negative < 0
if k is > 0 and all R<=0 then there is no solution

The analysis would be quite different if the equation were

and it would be different again if it were something like

Maria 2022-9-16

编辑：Maria 2022-9-16

@Walter Roberson I really appreciate your effort, thank you so much for answering me here, but I tried to find another solution that's why I deleted the question.

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