On odoo reporting, there is by default a total row giving the float or integer field sum, this field is on the measure selection box
There is necessarily a method allowing to do a sum operation (maybe using sum sql aggregate function), I want to override this method to allow me do a data average (maybe a svg sql aggeregate function) instead of sum, and just for one specified reporting (the one I'm developping), and not for all Odoo reportings.
Here is a picture that summarizes what I want to do.