[yt-users] Power Spectrum

Hi, I am trying to plot a power spectrum from some Enzo data. Trying to figure out how to do this, I stumbled across this post: http://lists.spacepope.org/pipermail/yt-users-spacepope.org/2012-March/00242... I followed the instructions here, extracting a covering grid and using numpy.fft. My question now is, how do I create the plot? I've tried using PlotCollection, but I get an 'unhashable type' error when I plug in my Fourier transformed data as one of the inputs to the add_profile_sphere command. So how would I go about plotting this? Is there an alternate way to use PlotCollection, or should I be using something else altogether? Thanks in advance, Tyler Berg