\name{trellis.object}
\alias{trellis.object}
\non_function{}
\title{A Trellis Plot Object}
\description{
  This class of objects is returned by high level lattice display
  functions, and is usually plotted by default by its `print' method.
}

\value{
  A trellis object, as returned by high level lattice functions like
  \code{\link{xyplot}}, is a list with the ``class'' attribute set to
  ``trellis''.  Many of the components of this list are simply the
  arguments to the high level function that produced the object.  Among
  them are:
 
  \itemize{
    \item{\code{as.table}}
    \item{\code{layout}}
    \item{\code{page}}
    \item{\code{panel}}
    \item{\code{prepanel}}
    \item{\code{main}}
    \item{\code{sub}}
    \item{\code{par.settings}}
    \item{\code{par.strip.text}}
    \item{\code{strip}}
    \item{\code{skip}}
    \item{\code{xlab}}
    \item{\code{ylab}}
  }

  Some other typical components are:

  \describe{
    \item{\code{index.cond}}{
      list with index for each of the conditioning variables
    }
    \item{\code{perm.cond}}{
      permutation of the order of the conditioning variables
    }
    \item{\code{aspect.fill}} {
      logical, whether \code{aspect} is ``fill''
    }
    \item{\code{aspect.ratio}}{
      numeric, aspect ratio to be used if \code{aspect.fill} is
      \code{FALSE}
    }
    \item{\code{call}} { call that generated the object. }
    \item{\code{condlevels}} {
      list with levels of the conditioning variables
    }
    \item{\code{legend}} {
      list describing the legend(s) to be drawn
    }
    \item{\code{panel.args}}{
      a list as long as the number of panels, each element being a list
      itself, containing the arguments in named form to be passed to the
      panel function in that panel.
    }
    \item{\code{panel.args.common}}{
      a list containing the arguments common to all the panel functions
      in \code{name=value} form
    }
    \item{\code{x.scales}}{
      list describing x-scale, can consist of several other lists,
      paralleling panel.args, if x-relation is not ``same''
    }
    \item{\code{y.scales}}{
      list describing y-scale, similar to \code{x.scales}
    }
    \item{\code{x.between}}{ numeric vector of interpanel x-space }
    \item{\code{y.between}}{ numeric vector of interpanel y-space }
    \item{\code{x.limits}}{
      numeric vector of length 2 or list, giving x-axis limits
    }
    \item{\code{y.limits}}{ similar to \code{x.limits} }
    
    %% also present, but not documented:
    %% x.num.limit x.used.at xlab.default
    %% y.num.limit y.used.at ylab.default
  }
}
\keyword{classes}