R: Scatter Plot with Smooth Curve Fitted by Loess

scatter.smooth {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, 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.
`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()`.

### 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`; `smoothScatter` for scatter plots with smoothed density color representation.

### Examples

    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)))

[Package stats version 3.1.2 Index]