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Move value at index i from one array to another array but at index 3 * i

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SAMUEL DAVID BERENSOHN
SAMUEL DAVID BERENSOHN on 16 Mar 2021
Answered: Stephen Cobeldick on 16 Mar 2021
I am trying to take an array [1 2 3] and scale the indices of each of the elements by three. So, as a result, I am hoping to have [1 0 0 2 0 0 3]. So far, I am using a for loop:
ytemp = zeros(length(input), 1);
for idx = 1:length(y_fft)
ytemp(idx * 3) = y_fft(idx);
end
Is there a better way to do this?

Answers (2)

Mohammad Sami
Mohammad Sami on 16 Mar 2021
Edited: Mohammad Sami on 16 Mar 2021
You can also do it this way.
a = [1 2 3];
b = [a; zeros(2,size(a,2))];
c = reshape(b,1,[]);
c(end-1:end) = [];
or as follows
a = [1 2 3];
c(1:3:(3*length(a))) = a

Stephen Cobeldick
Stephen Cobeldick on 16 Mar 2021
Robust and reasonably efficient:
n = 3; % scale
a = 1:3
a = 1×3
1 2 3
a(2:n,:) = 0;
a = a(1:1-n+end)
a = 1×7
1 0 0 2 0 0 3

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