MATLAB: How to find the column number of first zero element of each row

matrix manipulationvectorization

Hi,all. could you please tell me how to find the column number of first zero element of each row. eg. for the matrix in the picture, I want the output will be outputmatrix=[3;4;4;5;5;6;6;6;6;6;1;1;1;1;1]. Thank you!

Best Answer

This is your answer:

a =[ -1     3     0     0     0     0
      2     3     4     5     0     0
      1     2     1     0     0     0]
b = abs(a); % it is a trick which forces min to do not consider your negative numbers as minimum 
[~,ind] = min(b')

Related Solutions

MATLAB: How to find the index of first and last nonzero elements in each column

You could probably use

A = [0    0     0      0
	0     0     0      0
	1     0     4      8
	2     0     5      9
	3     1     6      7
	0     2     7      0
	0     0     0      0]
[rows, columns] = size(A)
B = zeros(2, columns)
for col = 1 : size(A, 2)
	B(1, col) = find(A(:, col), 1, 'first');
	B(2, col) = find(A(:, col), 1, 'last');
end

This gives

B =

3 5 3 3

5 6 6 5

which makes sense to me but I'm puzzled as to how you get

B=[3 12 17 24

5 13 21 26]

for your example. Can you explain?

MATLAB: Matrix padding with zero

Try this trick:

matrix2x2(3,3) = 0; % Add a row of zeros.

Then to turn the 5x2 into a 5x4:

b = rand(5,2)
array5x4 = padarray(b,[0,2],0, 'post')

Best Answer

Related Solutions

MATLAB: How to find the index of first and last nonzero elements in each column

MATLAB: Matrix padding with zero

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