How to remove repeated neighbour numbers?

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Amin Gan on 13 Nov 2015
Commented: Amin Gan on 13 Nov 2015
I have two A and B vectors, for example:
A=[9 9 8 7 6 6 6 7 9 9 10 9]
B=[1 1 2 3 1 2 3 2 3 2 4 5]
I want to keep only one number of each repeated value from A, and then make an average value from B.
At the end I want to get this:
Anew=[9 8 7 6 7 9 10 9]
Bnew=[1 2 3 2 2 2.5 4 5]
I do not want to lose the second/third 9 or second 7 of A.I just want to remove the repeated neighbour(s) value from A (with N numbers) and make an average of B.
Thank you

arich82 on 13 Nov 2015
Edited: arich82 on 13 Nov 2015
We can construct a mask to get the non-repeated elements of A. Then, cumsum(mask) will effectively give a phase number for each "new" (i.e. non-repeated) entry in A, which we can use to accumulate B:
A=[9 9 8 7 6 6 6 7 9 9 10 9]
B=[1 1 2 3 1 2 3 2 3 2 4 5]
mask = [true, diff(A) ~= 0];
Bnew = accumarray(cumsum(mask).', B, [], @mean).'
output:
Anew =
9 8 7 6 7 9 10 9
Bnew =
1.0000 2.0000 3.0000 2.0000 2.0000 2.5000 4.0000 5.0000
Please accept this answer if it helps, or let me know in the comments if I've missed something.
Amin Gan on 13 Nov 2015
Thank you very much.