I have two columns of data something like

1 10
2 11
2 12
2 11
2 13
3 15
4 16
5 17
5 19
5 17
5 17
6 20
6 20
6 20
6 21

From this I want to make another table of data
I want, where the numbers are duplicated in the LH column, to take that
number and put it in the new column once but have the values from the second
column averaged and put in as one value.

e.g.

new column would be

1 10
2 all the numbers corresponding to this value added and averaged.
3 15
4 16
5 all the numbers corresponding to this value added and averaged.


can this be done??


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Alternatively can I form two new columns by taking every fourth pair form
the original columns and putting them into the new columns.