how to assign rank to each row?

I have a matrix as follows:

A=[1	4;
    1	4;
    4	1;
    4	1;
    2	2;
    2	3;
    2	3;
    3	2;
    3	3];

I want to have another matrix like this-

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

Basically, I want to check each row and increase the corresponding value by 1 if iot does not matches with the preceding one. if it matche with the preceding one, I want to keep it as before.

How can I do this?

[Torsten]

For beginners, a for loop over the rows of A, inside the loop: a comparison of row i with row i-1 and an if-statement that adds 1 to element B(i-1) to get element B(i) if the two rows are not equal and that sets B(i) to B(i-1) if they are equal.

Answer 1

[Stephen23]

A = [1,4;1,4;4,1;4,1;2,2;2,3;2,3;3,2;3,3]

A = 9×2

1 4 1 4 4 1 4 1 2 2 2 3 2 3 3 2 3 3

B = cumsum([1;any(diff(A,1,1),2)])

B = 9×1

1 1 2 2 3 4 4 5 6

[Les Beckham]

Note that diff(A,1,1) is the same as diff(A) so this can be simplified as

A = [1,4;1,4;4,1;4,1;2,2;2,3;2,3;3,2;3,3]

A = 9×2

1 4 1 4 4 1 4 1 2 2 2 3 2 3 3 2 3 3

B = cumsum([1;any(diff(A),2)])

B = 9×1

1 1 2 2 3 4 4 5 6

[Stephen23]

"Note that diff(A,1,1) is the same as diff(A) so this can be simplified as"

Not quite. Consider what happens if one day A happens to have exactly one row... my code still works correctly for any size of matrix A, whereas not specifying the dimension is a latent bug.

For the same reason experienced MATLAB users often prefer to specify the (optional) dimension with many common functions e.g. MAX, MIN, MEAN, etc. when used with non-vector data.