# How can I create a new matrix from selected number of columns of an existing matrix

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Hugo on 27 Jan 2022
Answered: Benjamin Thompson on 27 Jan 2022
If I have a vector
x=[1,2,3,5]
and a matrix A with size 5*10
how can I get, concatenate and save the columns of the matrix A that are stated in the vector x, in a new matrix, called B
In my example above, if the first 5 columns of A are [2,3,4,5;4,5,4,2;7,5,6,4;5,6,5,4;3,4,3,4] ans must be:
B= [2,3,4,5;4,5,4,2;7,5,6,4;3,4,3,4]
I.e., the 4th column of the matrix A has been surpress in the writing of the matrix B

Benjamin Thompson on 27 Jan 2022
x =
1 2 3 5
>> A = rand(5,10)
A =
0.8147 0.0975 0.1576 0.1419 0.6557 0.7577 0.7060 0.8235 0.4387 0.4898
0.9058 0.2785 0.9706 0.4218 0.0357 0.7431 0.0318 0.6948 0.3816 0.4456
0.1270 0.5469 0.9572 0.9157 0.8491 0.3922 0.2769 0.3171 0.7655 0.6463
0.9134 0.9575 0.4854 0.7922 0.9340 0.6555 0.0462 0.9502 0.7952 0.7094
0.6324 0.9649 0.8003 0.9595 0.6787 0.1712 0.0971 0.0344 0.1869 0.7547
>> A(:,x)
ans =
0.8147 0.0975 0.1576 0.6557
0.9058 0.2785 0.9706 0.0357
0.1270 0.5469 0.9572 0.8491
0.9134 0.9575 0.4854 0.9340
0.6324 0.9649 0.8003 0.6787

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