If a=[1 2 3], b=[10 20 30], how to create c=[10 20 20 30 30 30]?

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The b matrix i'th element is repeated the number of times the given number in 'a' matrix and placed in matix 'c'. Also if a=[0 1 2], b=[10 20 30] how to get c=[20 30 30]??

Accepted Answer

Alfonso Nieto-Castanon
Alfonso Nieto-Castanon on 14 Jul 2014
c = cell2mat(arrayfun(@repmat,b,ones(size(a)),a,'uni',0));

More Answers (2)

Roger Stafford
Roger Stafford on 14 Jul 2014
Edited: Roger Stafford on 14 Jul 2014
Another way:
t = accumarray(cumsum([1,a]).',1);
c = b(cumsum(t(1:end-1)));

Jan
Jan on 14 Jul 2014
For large array this is efficient: FEX: RunLength
c = RunLength(a, b)

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