find the repeating numbers in order

I want to find the repeating numbers from the array in order. I have tried different repeating functions which tell me the frequency of the numbers, but I want to know the order of the repeating numbers. For example I have an array which is a=[1,1,1,1,1,2,2,2,2,2,1,1,1,1,4,4,4,5,5,5,7,7,2,2,2,2] and I want my function to give me the answer 1,2,1,4,5,7,2.

Answer 1

[Dyuman Joshi]

%Given your first element isn't 0
a=[1,1,1,1,1,2,2,2,2,2,1,1,1,1,4,4,4,5,5,5,7,7,2,2,2,2];
a(diff([0 a])~=0)

ans = 1×7

1 2 1 4 5 7 2

[MakM]

Thanks for the answer Joshi, what if my first element is zero? Because I have values from 0 to 5 in the array.

[Dyuman Joshi]

use any other value

a(diff([-1 a])~=0)

[Stephen23]

A robust solution that works for any values:

a = [0,1,1,1,1,1,2,2,2,2,2,1,1,1,1,4,4,4,5,5,5,7,7,2,2,2,2];
a([true,diff(a)~=0])

ans = 1×8

0 1 2 1 4 5 7 2

[MakM]

Thank you Stephan and Joshi.. It worked :)