[yt-users] Output data selection to ascii file or fits table

Hi, I would like to use yt to make selections of data from Enzo files (e.g. gas with certain properties in a particular volume), and then output the data to an external file like an ascii or fits table, to be analysed by other codes. Can you please tell me if such a tool is already available, or how I might be able to do it otherwise? Thanks.