Count numbers of identical rows

Hi there,

I am a new member here.

I have a sample dataset:

3 5
3 5
5 6
5 6
5 6
5 7 
6 8

I want the measure how many times does an identical row appears.

so the final result should be :

3 5 2
3 5 2
5 6 3
5 6 3
5 6 3
5 7 1
6 8 1

I have done it with a for loop but because my dataset is 8million x 2 if taking a lot of time and I am looking for an alternative solution.

Thanks

[Star Strider]

Panayiotis Christodoulou’s ‘Answer’ moved here:

there was an error on how the data were represented

please see atatched image

Answer 1

[Star Strider]

This works:

M = [3 5
    3 5
    5 6
    5 6
    5 6
    5 7 
    6 8];

[Mu,ia,ic] = unique(M, 'rows', 'stable');           % Unique Values By Row, Retaining Original Order
h = accumarray(ic, 1);                              % Count Occurrences
maph = h(ic);                                       % Map Occurrences To ‘ic’ Values

Result = [M, maph]

Result =

       3     5     2
       3     5     2
       5     6     3
       5     6     3
       5     6     3
       5     7     1
       6     8     1

[Panayiotis Christodoulou]

thanks for your help!

100% working

[Star Strider]

My pleasure!