How do I group data in a 2d-array?

I have several equally sized rows of data, like "values1", "values2" etc., including two-dimensional positions, "x_pos", and "y_pos". I can plot the data in a three-dimensional diagram using e.g. scatter3, or divide the number of values in bins with defined bin edges using histogram2, which is great.

However, I would like to process the data in each bin created by histogram2 so that I get the mean of all "values1" that have "x_pos" and "y_pos" within each bin, and present this in a 3d-graph with the bins as x-y (similar to histogram2) and the mean of values1 as z. How do I do this?