MATLAB Answers

Avoid for loop?

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grega
grega on 19 Dec 2018
Answered: Stephen Cobeldick on 19 Dec 2018
I want to generate arbitrary matrix of indeces, e.g.:
1 2 3 4
2 3 4 5
3 4 5 6
4 5 6 7
5 6 7 8
6 7 8 9
One can observe a series in it. I solved the problem as follows:
% --- Inputs
x = 1:9;
window = 4;
% --- creating the matrix
mm = length(x);
nb_rws = mm - window + 1;
y = ones(nb_rws,window);
for i = 1 : nb_rws
y(i,:) = x(i : i + window -1);
end
y
Is there a solution to avoid the for loop? Thanks..

Accepted Answer

madhan ravi
madhan ravi on 19 Dec 2018
Edited: madhan ravi on 19 Dec 2018
y=hankel((1:4),(4:9))'
Gives:
y =
1 2 3 4
2 3 4 5
3 4 5 6
4 5 6 7
5 6 7 8
6 7 8 9

More Answers (1)

Stephen Cobeldick
Stephen Cobeldick on 19 Dec 2018
Simpler:
>> hankel(1:6,6:9)
ans =
1 2 3 4
2 3 4 5
3 4 5 6
4 5 6 7
5 6 7 8
6 7 8 9

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