Hi everybody,

I'm a bit of a yt-newb, and I was wondering what the best way to handle a problem I'm working on it. 

Basically, I have a (large) list of locations (centers of galaxies), and I want to make a profile plot using the data from all of the shells a distance r > 10kpc, r < 100 kpsc from each of these centers.  I tried using a loop with the expression
x = pf.h.boolean([x, "AND", newShell])
to just build the data up over many iterations before finally using create_profile after the end of the loop, but this approach ran out of memory.  Is there a better way to get the sum of a large data set?

Thanks in advance for any help,
Thomas