# How can I mix two arrays?

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Alex Strongholm 2015-1-15

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]?

### 采纳的回答

Youssef Khmou 2015-1-15

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)];
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Stephen23 2015-1-15

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.
Stephen23 2015-1-15

### 更多回答（1 个）

Stephen23 2015-1-15

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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