Matlab: Vector indexing;

This is related to this post, and this post.

Q:
Suppose I have a vector like: v = [ 3 2 4 1 3 2...]
I want to obtain a new vector like: w = [3 3 3 2 2 4 4 4 4 1 3 3 3 2 2...]
basically every value repeates it's own number of times.

A1 (one-liner):

w = cell2mat(arrayfun(@(x) x+zeros(1,x), v, 'uni', 0))

A2:

v(v == 0) = [] % Need to get rid of zeros in the general case.
c = cumsum(v)
w = zeros(1,c(end))
w([1,c(1:end-1)+1]) = 1
w = v(cumsum(w))

Speed test:

% v = randi(800,1,90000)+1;
Method 1:
Elapsed
time is 1.997060 seconds.
Method 2:
Elapsed time is 1.630775 seconds.

Two methods are about same speed.