Analogue of unique function that keeps order and repetition (MATLAB)

Question

Suppose I have data: x = [3,3,1,1,1,2,2,1,1,1,1]
I would like to have the output:
y = [3,1,2,1]
With unique() function I could get:
z = [3,1,2]

But as you see, I'm missing the 'one' in the end. So, I tried to write a loop, but is in not doing what I though it should do. I was expecting it to delete one of the repeated values, and looping should have ensured that only one value remained. However, the output is:
x=[3,3,1,1,2,1,1]
The loop:
for i=1:length(x)
if x(i)==x(i+1)
x(i)=[];
end;
end;
Is there a way to generate output as in y? Where is the mistake in my loop?

Answer 1

If you would prefer a no-loop approach -

y = x([1 diff(x)~=0]==1)

Or

y = x([1 abs(diff(x))]>0)

Or

y = x([1 diff(x)]~=0)

Answer 2

Ask your question also asks, where the mistake in your code is, here comes the answer to that. Here comes variation of your code, which works:

x = [3,3,1,1,1,2,2,1,1,1,1];
for i=length(x):-1:2
    if x(i)==x(i-1)
        x(i)=[];
    end;
end;

1. In your loop i runs from 1 to length(x). In the last iteration there is no i+1 element left, as i already is equal to length(x).
2. When deleting elements of vectors in a loop, it is a common technique to loop from the end till the beginning, not from the beginning to the end. Then your code works just fine.