Finding min values of third column for rows with similar values

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ahmad Mohammadi
ahmad Mohammadi on 10 Aug 2020
Edited: ahmad Mohammadi on 11 Aug 2020
Hi,
I have a Table
2.0000 0 3.1971
1.0000 0 3.1971
3.0000 0 6.4662
1.0000 0 6.4662
3.0000 0 9.6356
2.0000 0 9.6356
2.0000 1 7
1.0000 1 5
3.0000 1 6
1.0000 1 10
3.0000 1 44
2.0000 1 12
Now, what I want is that find minimum value of third column for the first column with equal value in each loop of second column.
Maybe it is better to see the result what I mean.
2.0000 0 3.1971
1.0000 0 3.1971
3.0000 0 6.4662
2.0000 1 7
1.0000 1 5
3.0000 1 6
Really appreciate
  1 Comment
Stephen
Stephen on 11 Aug 2020
The example is not clear for me. You wrote that you want the "...minimum value of third column...", can you please explain why your example output contains this row:
...
2.0000 1 7
...
when the input matrix contains both of these rows
...
2.00000 1.00000 7.00000
...
2.00000 1.00000 2.00000
As far as I can tell, 2 is less than 7, so why does the expected output not contain the "minimum value" ?

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Accepted Answer

Stephen
Stephen on 11 Aug 2020
Edited: Stephen on 11 Aug 2020
>> M = [2.0000,0,3.1971;1.0000,0,3.1971;3.0000,0,6.4662;1.0000,0,6.4662;3.0000,0,9.6356;2.0000,0,9.6356;2.0000,1,7;1.0000,1,5;3.0000,1,6;1.0000,1,10;3.0000,1,44;2.0000,1,2]
M =
2.0000 0 3.1971
1.0000 0 3.1971
3.0000 0 6.4662
1.0000 0 6.4662
3.0000 0 9.6356
2.0000 0 9.6356
2.0000 1.0000 7.0000
1.0000 1.0000 5.0000
3.0000 1.0000 6.0000
1.0000 1.0000 10.0000
3.0000 1.0000 44.0000
2.0000 1.0000 2.0000
>> [U,X,Y] = unique(M(:,1:2),'stable','rows');
>> V = accumarray(Y,M(:,3),size(X),@min);
>> A = [U,V]
A =
2.0000 0 3.1971
1.0000 0 3.1971
3.0000 0 6.4662
2.0000 1.0000 2.0000
1.0000 1.0000 5.0000
3.0000 1.0000 6.0000
  1 Comment
ahmad Mohammadi
ahmad Mohammadi on 11 Aug 2020
Thats great. I spent like 5 hours to reach a very bad coding. But, you saved me
Thanks,

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