scatter.smooth             package:stats             R Documentation

Scatter Plot with Smooth Curve Fitted by Loess

Description:

     Plot and add a smooth curve computed by 'loess' to a scatter plot.

Usage:

     scatter.smooth(x, y = NULL, span = 2/3, degree = 1,
         family = c("symmetric", "gaussian"),
         xlab = NULL, ylab = NULL,
         ylim = range(y, prediction$y, na.rm = TRUE),
         evaluation = 50, ...)

     loess.smooth(x, y, span = 2/3, degree = 1,
         family = c("symmetric", "gaussian"), evaluation = 50, ...)

Arguments:

     x,y: the 'x' and 'y' arguments provide the x and y coordinates for
          the plot.  Any reasonable way of defining the coordinates is
          acceptable.  See the function 'xy.coords' for details.

    span: smoothness parameter for 'loess'.

  degree: degree of local polynomial used.

  family: if '"gaussian"' fitting is by least-squares, and if
          'family="symmetric"' a re-descending M estimator is used.

    xlab: label for x axis.

    ylab: label for y axis.

    ylim: the y limits of the plot.

evaluation: number of points at which to evaluate the smooth curve.

     ...: graphical parameters.

Details:

     'loess.smooth' is an auxiliary function which evaluates the
     'loess' smooth at 'evaluation' equally spaced points covering the
     range of 'x'.

Value:

     For 'scatter.smooth', none.

     For 'loess.smooth', a list with two components, 'x' (the grid of
     evaluation points) and 'y' (the smoothed values at the grid
     points).

See Also:

     'loess'

Examples:

     require(graphics)

     with(cars, scatter.smooth(speed, dist))

