Hi all! Is there any possible way to modify a (non-derived) field in a Gadget Binary Dataset and update the computation of the derived (in particular, deposited) fields to reflect this change? For example, I would like to substract a fixed velocity from all Gas particles (as to account for the Sun's velocity) and recalculate the smoothed velocity fields accordingly. As a reference, modifying the in-disk fields the following way works, but has no effect on the derived_fields: ds = yt.load('path/to/dataset', unit_base = unit_base) for i in range(num_particles): ds.r['Gas', 'Velocities'][i] -= ds.arr([100,100,100], 'code_velocity') #substracting some fixed array Any help would be very much appreciated. Thanks is advance (and happy holidays!) Martin