Smoothes intensities by loess fitting.

## Usage

```
smooth_loess(x, y, ...)
# S4 method for numeric,numeric
smooth_loess(x, y, span = 0.75, ...)
# S4 method for ANY,missing
smooth_loess(x, span = 0.75, ...)
```

## Arguments

- x, y
A

`numeric`

vector. If`y`

is missing, an attempt is made to interpret`x`

in a suitable way (see`grDevices::xy.coords()`

).- ...
Extra arguments to be passed to

`stats::loess()`

.- span
An

`integer`

specifying the degree of smoothing (see`stats::loess()`

).

## Value

Returns a `list`

with two components `x`

and `y`

.

## See also

Other smoothing methods:
`smooth_rectangular()`

,
`smooth_savitzky()`

,
`smooth_triangular()`

,
`smooth_whittaker()`

## Examples

```
## Simulate data with some noise
x <- seq(-4, 4, length = 100)
y <- dnorm(x) + rnorm(100, mean = 0, sd = 0.01)
## Plot spectrum
plot(x, y, type = "l", xlab = "", ylab = "")
## Rectangular smoothing
unweighted <- smooth_rectangular(x, y, m = 3)
plot(unweighted, type = "l", xlab = "", ylab = "")
## Triangular smoothing
weighted <- smooth_triangular(x, y, m = 5)
plot(weighted, type = "l", xlab = "", ylab = "")
## Loess smoothing
loess <- smooth_loess(x, y, span = 0.75)
plot(loess, type = "l", xlab = "", ylab = "")
## Savitzky–Golay filter
savitzky <- smooth_savitzky(x, y, m = 21, p = 2)
plot(savitzky, type = "l", xlab = "", ylab = "")
## Whittaker smoothing
whittaker <- smooth_whittaker(x, y, lambda = 1600, d = 2)
plot(whittaker, type = "l", xlab = "", ylab = "")
```