scatter.smooth: 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, pred$y, na.rm = TRUE),
    evaluation = 50, …, lpars = list())
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. Can be abbreviated.

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.

…

For scatter.smooth(), graphical parameters, passed to plot() only. For loess.smooth, control parameters passed to loess.control.

lpars

a list of arguments to be passed to lines().

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).

Details

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

Examples

Run this code

require(graphics)

with(cars, scatter.smooth(speed, dist))
## or with dotted thick smoothed line results :
with(cars, scatter.smooth(speed, dist, lpars =
                    list(col = "red", lwd = 3, lty = 3)))