MATLAB: Combining data with matching elements in the first two columns

Question

Hello, I have a data table that looks like this

920  381  784  0
920  381  0  21.4375
23  388  1703  0
23  388  0  4.109375
445  487  304  0
445  487  0  15.09375
1100  506  1480  0
1100  506  0  28.234375
245  520  454  0
245  520  0  40.21875

For all the entries where the first two columns match (ie, the first two rows), I would like to combine those two rows into one. So these two rows:

920  381  784  0
920  381  0  21.4375

Will become

920  381  784  21.4375

And so on for the rest of the data set. I would appreciate any help.

Thanks

Answer 1

Here's one way:

[~,i,j]=unique(M(:,1:2),'rows');
[M(i,[1 2]),accumarray(j,M(:,3)),accumarray(j,M(:,4))]

where M is your original array.

EDIT: Original solution only gave the last two columns, so I fixed it to give all the columns you need.