

   sortedXyData {nls}                           R Documentation

   CCrreeaattee aa ssoorrtteeddXXyyDDaattaa oobbjjeecctt

   DDeessccrriippttiioonn::

        This is a constructor function for the class of `sort-
        edXyData' objects.  These objects are mostly used in
        the `initial' function for a self-starting nonlinear
        regression model, which will be of the `selfStart'
        class.

   UUssaaggee::

        sortedXyData(x, y, data)

   AArrgguummeennttss::

          x: a numeric vector or an expression that will evalu-
             ate in `data' to a numeric vector

          y: a numeric vector or an expression that will evalu-
             ate in `data' to a numeric vector

       data: an optional data frame in which to evaluate
             expressions for `x' and `y', if they are given as
             expressions

   VVaalluuee::

        A `sortedXyData' object. This is a data frame with
        exactly two numeric columns, named `x' and `y'.  The
        rows are sorted so the `x' column is in increasing
        order.  Duplicate `x' values are eliminated by averag-
        ing the corresponding `y' values.

   AAuutthhoorr((ss))::

        Jose Pinheiro and Douglas Bates

   SSeeee AAllssoo::

        `selfStart', `NLSstClosestX', `NLSstLfAsymptote',
        `NLSstRtAsymptote'

   EExxaammpplleess::

        library( nls )
        data( DNase )
        DNase.2 <- DNase[ DNase$Run == "2", ]
        sortedXyData( expression(log(conc)), expression(density), DNase.2 )

