How to change a matrixvalue dependent on the previous matrixvalue?

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Klaas
Klaas 2017-2-20
回答： Akira Agata 2017-2-20
Hellow
I made this code including for loops but this is very time consuming. My goal is that in the T1 matrix a 1 in placed when the value of matrix T changes from 0 to 1 when looking down in the collum. When the next value of T is again a 1 the T1 matrix must give a 0. So I want to count the number of times the matrix value of T changes from 0 to 1. Has anyone a quicker alternative then this?
for ii=1:4; for jj=1:9 if T(jj+1,ii)>0 && T(jj,ii)<T(jj+1,ii); T1(jj,ii)=1; end end end
Many thanks in advance!

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Akira Agata
Akira Agata 2017-2-20
I think the following code should be alternative.
idx = [(T(2:end,:) > 0) & (T(1:end-1,:) < T(2:end,:)); logical(zeros(1,size(T,2)))]
T1(idx) = 1;
Let me check whether it works correctly by following.
T = randi([0 1], 10, 4); % Randomly generated 0/1 array
T1 = zeros(size(T));
T2 = zeros(size(T));
% Original code
for ii=1:4;
for jj=1:9
if T(jj+1,ii)>0 && T(jj,ii)<T(jj+1,ii);
T1(jj,ii)=1;
end
end
end
% Proposed code
idx = [(T(2:end,:) > 0) & (T(1:end-1,:) < T(2:end,:)); logical(zeros(1,size(T,2)))]
T2(idx) = 1;
The result isequal(T1,T2) becomes true.
I hope this answer will help you.

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