| lowess {stats} | R Documentation |
This function performs the computations for the
LOWESS smoother (see the reference below).
lowess returns a list containing components
x and y which give the coordinates of the smooth.
The smooth should be added to a plot of the original
points with the function lines.
lowess(x, y = NULL, f = 2/3, iter = 3,
delta = 0.01 * diff(range(xy$x[o])))
x, y |
vectors giving the coordinates of the points in the scatter plot. Alternatively a single plotting structure can be specified. |
f |
the smoother span. This gives the proportion of points in the plot which influence the smooth at each value. Larger values give more smoothness. |
iter |
the number of robustifying iterations which should be
performed.
Using smaller values of iter will make lowess run faster. |
delta |
values of x which lie within delta
of each other are replaced by a single value in the output from
lowess. Defaults to 1/100th of the range of x. |
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
Cleveland, W. S. (1979) Robust locally weighted regression and smoothing scatterplots. J. Amer. Statist. Assoc. 74, 829–836.
Cleveland, W. S. (1981) LOWESS: A program for smoothing scatterplots by robust locally weighted regression. The American Statistician, 35, 54.
loess, a newer
formula based version of lowess (with different defaults!).
plot(cars, main = "lowess(cars)")
lines(lowess(cars), col = 2)
lines(lowess(cars, f=.2), col = 3)
legend(5, 120, c(paste("f = ", c("2/3", ".2"))), lty = 1, col = 2:3)