Plot and add a smooth curve computed by `loess`

to a scatter plot.

```
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, …)

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`

.

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).

`loess.smooth`

is an auxiliary function which evaluates the
`loess`

smooth at `evaluation`

equally spaced points
covering the range of `x`

.

`loess`

; `smoothScatter`

for scatter plots
with smoothed *density* color representation.

# NOT RUN { 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))) # }