Eliminate repeating values in column, but keep one set and append the following column's value to kept values in first column:

Need to convert matrix A(250000x2) to A(14x250000) where values in first column repeat. Values in second column next to repeated values from first column need to be appended to the rows corresponding to that repeated value (and repeated values removed). Basically shifting. I can use unique to pull the values from the first column along with their index, but I am having trouble finding a way to transfer those values "up". Any suggestions?

[14 #1; 13 #1;...;1 #1;14 #2; 13 #2;...;1 #2;...14 #n; 13 #n;...;1 #n]

 to

[14 #1 #2...#n;13 #1 #2...#n;...;1 #1 #2...#n]

Answer 1

[Ameer Hamza]

Try

splitapply(@(x) {x}, A(:,2), findgroups(A(:, 1)));

[fernando aguirre]

Great suggestion! I'll update the success of the implementation if with works thoroughly after turning cells to column vectors and such!

[Ameer Hamza]

You are welcome.

[fernando aguirre]

It works like a charm! Thank you once again!