Sort rows of a matrix based on a specific array

Hi everyone,

Let us assum Matrix A and array B as follows:

A = [1 0 1
     2 0 0
     4 0 0
     3 1 1
     6 0 0
     5 0 0]
 
 B = [3 4 1]

Array B always include values stored in the first column of Matrix A. So, I want to sort rows of Matrix A based on Array B. Whatever comes first in Array B must come first in Matrix A. Moreover, I do not want to change the position of any other rows in Matrix A that their values (first column) do not exist in Array B.

Having said this, sorted version of Matrix A based on Array B will be as follows:

 An = [3 1 1
       2 0 0
       4 0 0
       1 0 1
       6 0 0
       5 0 0]

Would you please guide me what is the fastest way to do this?

Regards,

Amir

Answer 1

[Stephen23]

>> [X,Y] = ismember(A(:,1),B);
>> [~,Z] = sort(Y(X));
>> T = A(X,:);
>> A(X,:) = T(Z,:)
A =
   3   1   1
   2   0   0
   4   0   0
   1   0   1
   6   0   0
   5   0   0

[Amirhossein Moosavi]

Thanks Stephen, your code works!

Answer 2

[madhan ravi]

v = sort(B);
A([1, v(end)], :) = A([v(end), 1], :)

[Amirhossein Moosavi]

Thank you, but it does not work for some cases. Let us say Array B is as follows:

B = [3 4]

Then, Matrix A becomes like this (using your code):

A = [3 1 1
     2 0 0
     4 0 0
     1 0 1
     6 0 0
     5 0 0]

While, Matrix A must have become as follows:

 A = [1 0 1
      2 0 0
      3 1 1
      4 0 0
      6 0 0
      5 0 0]

[madhan ravi]

I misunderstood the question.