# How can I save 3 matrices created by for loop to save in a single matrix?

27 views (last 30 days)
I have a for loop which outputs the following matrices after each iteration: [3,4;5,6], [8,5;2,4], [1,8;3,7]
I want to save these outputs into a single matrix and it should be this: final=[3,4;5,6;8,5;2,4;1,8;3,7]
The size of the 'final' matrix is known to me.
How do I do this?

Rishabh Rathore on 5 Jun 2018
Edited: Rishabh Rathore on 5 Jun 2018
Since you know the size of the final matrix, first you can initialize the matrix of that size and then assign the appropriate row index.
for example the following code creates the desired matrix from given output of each iterations
matrix=zeros(6,2) % only 3 iteration creating 2*2 matrix.
for i=1:3
output=x %2*2 matrix;
matrix((2*i-1),:)=output(1,:);
matrix(2*i,:)=output(2,:);
end
The easier way would be to just append the output of each iteration, but it could be slow as the final matrix won't be pre-allocated, but here's the code, in case you need it.
matrix=[];
for i=1:end
output=x %2*2 matrix;
matrix=[matrix; output];

deepak kumar on 5 Jun 2018
a = [3,4,5,6]
b = [8,5;2,4]
c = [1,8;3,7]
d = vertcat(a,b,c)
or we can also do as temp =[]; for i =1:n %let say a have your output temp =[temp;a] end

Suraj Sudheer Menon on 22 Jun 2020
let x,y,z be the 3 iteration output vectors.
ans=[x ; y ; z]
% This creates a new vector by combining the above vectors. The semi colon indicates seperate rows(vertically joining).