MATLAB: How to repeat an array based on another array

repeat array

Greetings

I am trying to repeat an array based on another array e.g

Repeat element of array A based on the elements of array B

A= [ 1 2 3 4 ] 
B= [ 2 3 1 2]

the resulted array should be ( first element of A that is 1 repeated 2 times which is the first element of array B and so on )

C= [ 1 1 2 2 2 3 4 4 ]

C = repelem(A,B)

You can use repelem function to accomplish your question

a =
       1     2     3     4
>> repelem(a, 3)
ans =
       1     1     1     2     2     2     3     3     3     4     4     4

If you have MATLAB 2015a or more recent then use repelem:

 repelem(A,B)

otherwise:

 cell2mat(arrayfun(@(a,b)repmat(a,1,b),A,B,'Uni',0))

although a loop may well be faster.