# Extract columns into new variables efficently

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Hi Mathwork's community,
So I have a Matrix A such as:
A= [1 1 2 2 3 3 1 1 2 2 3 3; 1 1 2 2 3 3 1 1 2 2 3 3];
And a matrix B, which is the matrix that I'd like to separate into three different variables. (Note: There will always be three variables).
B = [10 20 30 40 50 60 70 80 90 100 110 120; 1 2 3 4 5 6 7 8 9 10 11 12];
Variable1 corresponds to B positions where A values are equal to 1, Variable2 corresponds to B positions where A values are equal to 2 and Variable3 corresponds to B positions where A values are equal to 3. The expected output should be:
Variable1 =[10 20 70 80; 1 2 7 8]
Variable2 = [30 40 90 100 ; 3 4 9 10]
Variable3 = [50 60 110 120; 5 6 11 12]
Santos
##### 2 CommentsShowHide 1 older comment
Santos García Rosado on 21 Apr 2021
Hello Walter. Thank's for the question. Clearly, I didn't make my-self clear enoguh on that part. All the rows of A will be equal to the first row and will always be 1, 2 and 3 values.

Jeff Miller on 21 Apr 2021
A= [1 1 2 2 3 3 1 1 2 2 3 3; 1 1 2 2 3 3 1 1 2 2 3 3];
B = [10 20 30 40 50 60 70 80 90 100 110 120; 1 2 3 4 5 6 7 8 9 10 11 12];
type1 = A(1,:) == 1;
Variable1 = B(:,type1);
% et cetera
Santos García Rosado on 22 Apr 2021
Thank's Jeff. That'll do.

R2021a

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