Hi Folks, I wanted to bring them problem to your attention as well as show you an extremely hacky attempt at solving it. The add_profile_sphere and add_phase_sphere methods of PlotCollectionInteractive appear to have a bug in them. When I do: In [3]: p = pc.add_phase_sphere(0.015, 'pc', ["Density", "Temperature", "CellMassMsun"], weight = None) I get the following traceback: TypeError Traceback (most recent call last) /indirect/o/atmyers/yt/src/yt-trunk-svn/scripts/iyt in <module>() ----> 1 2 3 4 5 /indirect/o/atmyers/yt/src/yt-trunk-svn/yt/raven/plot_collection.py in pylabify(self, *args, **kwargs) 1440 kwargs['axes'] = self.pylab.gca() 1441 kwargs['figure'] = self.pylab.gcf() -> 1442 retval = func(self, *args, **kwargs) 1443 retval._redraw_image() 1444 retval._fig_num = new_fig.number /indirect/o/atmyers/yt/src/yt-trunk-svn/yt/raven/plot_collection.py in add_phase_sphere(self, radius, unit, fields, center, cmap, weight, accumulation, x_bins, x_log, x_bounds, y_bins, y_log, y_bounds, lazy_reader, id, axes, figure, fractional) 1128 x_bins, x_log, x_bounds, 1129 y_bins, y_log, y_bounds, -> 1130 lazy_reader, id, axes, figure, fractional) 1131 p["Width"] = radius 1132 p["Unit"] = unit /indirect/o/atmyers/yt/src/yt-trunk-svn/yt/raven/plot_collection.py in pylabify(self, *args, **kwargs) 1440 kwargs['axes'] = self.pylab.gca() 1441 kwargs['figure'] = self.pylab.gcf() -> 1442 retval = func(self, *args, **kwargs) 1443 retval._redraw_image() 1444 retval._fig_num = new_fig.number TypeError: add_phase_object() got multiple values for keyword argument 'axes' The same thing happens when I use pc.add_profile_sphere, but only with PlotCollectionInteractive. Using the same methods with PlotCollection works fine. The problem seems to be that the wrapper that "Interactifies" the PlotCollection methods assumes that you will not call them with "axes" or "figure" in the positional arguments. However, as currently coded, the add_phase_sphere and add_profile_sphere methods both call add_phase_object or add_profile_object, and when they do so they pass an axes and figure in the positional arguments. Probably the best way to fix this is to re-write the wrapper function to not assume that you don't have an axes or figure in *args, but in the meantime I've got mine to work just by changing add_profile_sphere and add_phase_sphere like so (docstring snipped) def add_phase_sphere(self, radius, unit, fields, center = None, cmap=None, weight="CellMassMsun", accumulation=False, x_bins=64, x_log=True, x_bounds=None, y_bins=64, y_log=True, y_bounds=None, lazy_reader=True, id=None, axes = None, figure = None, fractional=False): if center is None: center = self.c r = radius/self.pf[unit] data_source = self.pf.hierarchy.sphere(center, r) p = self.add_phase_object(data_source, fields, cmap, weight, accumulation, x_bins, x_log, x_bounds, y_bins, y_log, y_bounds, lazy_reader, id, axes = axes, figure = figure, fractional = fractional) p["Width"] = radius p["Unit"] = unit p["Axis"] = None return p So now the call to add_phase_object takes keyword arguments instead of positional ones for axes and figure. I made the same change to add_profile_sphere, and they work for me in interactive mode now. Thanks, Andrew M