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

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?

Answer 1

[Mohammad Sami]

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

Answer 2

[Stephen23]

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