How can I mix two arrays?

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Alex Strongholm
Alex Strongholm on 15 Jan 2015
Edited: Stephen23 on 18 Jan 2015
Given A=[1 3 5 7 9] and B=[2 4 6 8], how can I create C=[1 2 3 4 5 6 7 8 9]?

Accepted Answer

Youssef  Khmou
Youssef Khmou on 15 Jan 2015
Edited: Youssef Khmou on 15 Jan 2015
This question is general due to the variation of array dimensions, however for a particular case you described, vectors A and B can be mixed by single loop, so the following scheme is valid only when dim(A)=dim(B)+1 as in the example :
A=[1 3 5 7 9];
B=[2 4 6 8];
n=min(length(A),length(B));
C=[];
for t=1:n
C=[C A(t) B(t)];
end
C=[C A(end)];
  3 Comments
Stephen23
Stephen23 on 15 Jan 2015
Edited: Stephen23 on 18 Jan 2015
This answer is very poor use of MATLAB.
The use of a for loop and concatenating scalar values onto the end of with every iteration is poor coding practice in MATLAB. If the arrays are large, then this will be slow as MATLAB keeps expanding the array and copying it to new memory. One solution is to preallocate the array.
For a much neater and simpler solution see my answer below.

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More Answers (1)

Stephen23
Stephen23 on 15 Jan 2015
Edited: Stephen23 on 16 Jan 2015
This can be done simply using indexing, without any loops:
>> A = [1,3,5,7,9];
>> B = [2,4,6,8];
>> C(1:2:2*numel(A)) = A;
>> C(2:2:end) = B
C =
1 2 3 4 5 6 7 8 9
This solution also assumes that numel(A)==numel(B)+1.
Most importantly, for larger arrays this code will be much faster than the accepted solution, so it is the most universal solution.

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