Repeat specific elements in vector with keeping the basic vector

Hi All,

I have been trying to create a new vector based on old one, by repeating specific elements, I have been looking for a lot of arguments, I found the easily one is repelem, but unfortunately, it repeats elements wtihout keeping the basic one...

I mean I have this vector= [-7.5 -5 -2.5 0 2.5 5 7.5], I'd like the output to be: [-7.5 -5 -2.5 -2.5 0 2.5 5 5 7.5], NOT as my code output

So I need to create the same vector with repeating each 3 elements....

clear all; clc;
x=[-7.5 -5 -2.5 0 2.5 5 7.5];
y=repelem(x(3:3:end),2)

I hope anyone can realy help !!!

Answer 1

[Thiago Henrique Gomes Lobato]

repelem indeed solves your problem, you just have to give the repetition indexes as a element-wise argument and pass the whole vector

x=[-7.5 -5 -2.5 0 2.5 5 7.5];
y = repelem(x,[1 1 2 1 1 2 1]) % Easier to understand what is happening

% Vectorized solution
Indices = ones(size(x));
Indices(3:3:end) = 2;
y = repelem(x,Indices) % In

y =

   -7.5000   -5.0000   -2.5000   -2.5000         0    2.5000    5.0000    5.0000    7.5000