Get the row index of matrix where the first 3 columns are equal in two matrix

Hi I have the matrix A and the matrix B

A = [1 2 3 6 8 9;3 5 1 7 8 89;23 2 4 5 56 7;11 12 14 15 16 17]

B = [1 2 3;11 12 13]

I need to get the Index where the i row of B are in A. In this case get the vector

Indices = [1 4]

to finally obtain the matrix A only with the common row with B, in this case,

D = [1 2 3 6 8 9;11 12 14 15 16 17]

I wrote the next code, but this it seems to be low efficient (takes to long to find 135 rows of B in 27000 rows of A in my real case). Is there a different aproach to be more efficient?

A2 = A(:,1:3);
[rowB,colB] = size(B)

for i = 1:rowB;

      B2 = B(i,:);

      D = nlfilter(A2, [1 3], @(x) (isequal(x,B2)))
      [rowD,colD] = find(D)
      Indices(i) = rowD

end

D = A(Indices,:);

Thanks for your help.

[James Tursa]

In your example, it is not clear why the 2nd row of B [11 12 13] matches the row of A [11 12 14 15 16 17]. Is this a typo? Or what is the rule for matching?

[AMANECH77]

Sorry. You´re right. The matrix B is:

B = [1 2 3;11 12 14]

[James Tursa]

Will B always match A in the first three columns? Or could it match in any of the columns?

[James Tursa]

Will B always match A in the first three columns? Or could it match in any of the columns?

[AMANECH77]

B must match A in the first three columns.

Answer 1

[James Tursa]

Assuming the match is always in the first three columns (caution, untested):

k = ismember(A(:,1:3),B,'rows');
D = A(k,:);

[AMANECH77]

Thanks, it works for my needs.