How to find a vector multiple times in an array?

Good day to all,

I am facing the problem that I need to quickly find the positions of duplicates of a vector in an array.

Currently I am doing this with a for-statement. For this I run the whole array and compare the rows with my vector. The row has the same length as the vector. This leads to very high run times.

With "ismember" I can check if there are duplicates and also determine the position of the first duplicate. However, the vector can occur several times in the array.

Example:

A = [1 3 4] %x,y,z-coordinates - vector

B = [2 3 4; 1 3 4; 5 5 6; 3 4 6; 1 3 4]; %array

The goal here would be to get the indexes 2 and 5.

Can anyone help me with this?

Many greetings

Tom

Answer 1

[Chunru]

A = [1 3 4] %x,y,z-coordinates - vector

A = 1×3

1 3 4

B = [2 3 4; 1 3 4; 5 5 6; 3 4 6; 1 3 4]; %array
find(all(A==B, 2))      % 2 is for row dim

ans = 2×1

2 5

Answer 2

[Bruno Luong]

A = [1 3 4]; %x,y,z-coordinates - vector
B = [2 3 4; 1 3 4; 5 5 6; 3 4 6; 1 3 4]; %array

% which row match
find(ismember(B,A,'rows'))

ans = 2×1

2 5

[Tom Engels]

Thank you all very much. It works great!