MATLAB: How to find duplicate values in 2d matrix

duplicate findgroups unique

Hello,
I have the following matrix 
M =[    1540	1685	6.90000000000000	24.2000000000000	14.6000000000000;
        1540	1700	9.90000000000000	15.5000000000000	17.9000000000000;
        1540	1701	9.90000000000000	12.4000000000000	17.9000000000000;
        1540	1685	6.90000000000000	23.5000000000000	14.600000000000
        1540	1700	9.90000000000000	15	                17.9000000000000;
        1540	1701	9.90000000000000	13.3000000000000	17.9000000000000;
        1540	1680	6.90000000000000	26.2000000000000	14.4000000000000;
        1540	1689	6.90000000000000	26.1000000000000	14.6000000000000;
        1540	1680	6.90000000000000	24	                14.6000000000000;
        1540	1680	6.90000000000000	24	                14.5000000000000;
        1540	1688	7	                23.5000000000000	14.6000000000000;
    ]
And I would like to identify the duplicates of that matrix based on the first two colums and extract them to furher operations. Thus, I would like to have a way to get a sub-matrices of the form
M11 = [ 1540	1700	9.90000000000000	15.5000000000000	17.9000000000000;
        1540	1700	9.90000000000000	15	                17.9000000000000;
      ]
M22 =[ 1540	1680	6.90000000000000	26.2000000000000	14.4000000000000;
       1540	1680	6.90000000000000	24	                14.5000000000000;
     ]
How can I achieve this? Could I use findgroups for this purpose?
Thanks in advance

Best Answer

You can indeed use findgroups. You should supply the first two columns as separate inputs.
G=findgroups(M(:,1),M(:,2));
Then I would suggest looping through the group IDs and fill a cell array. Don't use numbered variables, because they are hard to use in further analysis.
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