Create a new matrix

Let A a matrix and B a vector defined by :

A=[ 4 2
    7 4
    3 5
    6 8
    8 1];

B= [4 6 7 8];

I wish to know how to create a new matrix C which is a part of matrix A but necessary contain an element of the vector B, given by

C = [ 7 4
      6 8];

If anyone could help , I'd greaty appreciate it.

[Sam Chak]

Sounds like an IQ puzzle.

What is the governing rule for the contruction of Matrix ?

A brief glance at Matrix shows that:

C = [A(2,:); A(4,:)]

[Walter Roberson]

C = A([2 4],:)

Answer 1

[Bruno Luong]

A=[ 4 2
    7 4
    3 5
    6 8
    8 1];
B= [4 6 7 8];
C = A(all(ismember(A,B),2),:)

C = 2×2

7 4 6 8

[Yamina chbak]

Yees, It worked. Thanks!

[Yamina chbak]

Hi @Bruno Luong. I like your answer and I would like to learn from you. If you can help, I have an question about this problem but in the case of the matix A has 3 or 6 column , for example:

A=[ 4 2 5

7 4 3

3 5 1

6 8 1];

I wish to learn how to create a new matrix C which is a part of A and necessary to have two column and contain the elements of B:

B=[5 8 2 6 1]

to get like:

C = [2 5

5 1

6 8];

I will glad if you could help me.

[Bruno Luong]

This code select the first two matched if there is more than 2 (like the last row of A):

A=[ 4 2 5
    7  4 3
    3  5 1
    6 8  1];
B=[5 8 2 6 1];

At = A.';
tf = ismember(At,B);
tf = tf & cumsum(tf,1)<=2;
C = reshape(At(tf),2,[]).'

C = 3×2

2 5 5 1 6 8

[Yamina chbak]

Yes, thanks you @Bruno Luong I understand this code. Thanks you again