deletions | additions       diff --git a/2-Structure.tex b/2-Structure.tex  index 0217af2..d4fff0c 100644  --- a/2-Structure.tex  +++ b/2-Structure.tex 
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\label{sec:df}  Data for each particle type (e.g., dark matter, gas, etc.) is stored in a separate \code{PartType} dataframe and indexed by particle ID number.   Individual fields can be loaded into the dataframes and deleted at will, with coherent slicing across multiple data fields, courtesy of \code{pandas}.   The base \code{PartType} objects, \code{PartTypeNbody} and \code{PartTypeSPH}, are standard \code{pandas} dataframes, dataframes  with additional functionality for loading standard \textsc{gadget} particle fields from HDF5, converting units, and performing coordinate transformations. As such, \code{gadfly} dataframes retain all the capabilities of the \code{pandas.DataFrame} from which they inherit, and any operation that creates a new dataframe instance returns a standard \code{pandas} dataframe.  Nonstandard particle fields can be easily loaded into \code{gadfly} as well; fields loaded in this manner simply lack automated unit conversion.