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Remove duplicate 1s from matrix columns

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Mitchell Crem
Mitchell Crem on 24 Jan 2021
Commented: Image Analyst on 25 Jan 2021
Suppose I have the following logical matrix,
qq =
3×5 logical array
1 0 1 1 1
1 1 0 1 1
1 0 0 0 1
I'm trying to write a few lines which would allow me to set each column to possess only a single 1 by setting additional 1s to 0. The output should look like the following.
qq =
3×5 logical array
1 0 1 1 1
0 1 0 0 0
0 0 0 0 0
:)

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Answers (1)

Image Analyst
Image Analyst on 25 Jan 2021
Mitchell, try this:
qq = logical([...
1 0 1 1 1
1 1 0 1 1
1 0 0 0 1])
[rows, columns] = size(qq);
for col = 1 : columns
highestOne = find(qq(:, col), 1, 'first');
if ~isempty(highestOne)
qq(highestOne + 1 : end, col) = false;
end
end
qq % Show in command window.
You see:
qq =
3×5 logical array
1 0 1 1 1
1 1 0 1 1
1 0 0 0 1
qq =
3×5 logical array
1 0 1 1 1
0 1 0 0 0
0 0 0 0 0

  2 Comments

Mitchell Crem
Mitchell Crem on 25 Jan 2021
Looks good, but I was looking for something vectorised. Apologies, I should've specified that.
Image Analyst
Image Analyst on 25 Jan 2021
And I gave it to you. Saying qq(:, col) means to get the column vector from the matrix.

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