lowess {stats} | R Documentation |

## Scatter Plot Smoothing

### Description

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`

.

### Usage

lowess(x, y = NULL, f = 2/3, iter = 3,
delta = 0.01 * diff(range(xy$x[o])))

### Arguments

`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` . |

### References

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.

### See Also

`loess`

, a newer
formula based version of `lowess`

(with different defaults!).

### Examples

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)

[Package

*stats* version 2.2.1

Index]