Plots spectral curves with various levels of loess smoothing to help decide which
loess parameters are best for subsequently smoothing the data (e.g. via `procspec()`

).

```
plotsmooth(
rspecdata,
minsmooth = 0.05,
maxsmooth = 0.2,
curves = 5,
specnum = "ALL",
ask = TRUE
)
```

## Arguments

- rspecdata
(required) a data frame, possibly of class `rspec`

, which
contains a column containing a wavelength range, named 'wl', and spectra
data in remaining columns.

- minsmooth
the minimum f value of the loess function to visualize (defaults to `0.05`

).

- maxsmooth
the maximum f value of the loess function to visualize (defaults to `0.20`

).

- curves
the number of curves to display on the same plot (defaults to `5`

).

- specnum
the number of spectral curves, from the data frame, to visualize (defaults to `ALL`

).

- ask
logical. if `TRUE`

, asks for user input before changing plot pages

## Value

Series of plot with curves processed with varying level of loess smoothing

## Examples

```
# Load reflectance spectra
data(sicalis)
# Visualise the spectral reflectance curves across a range of smoothing levels
plotsmooth(sicalis, minsmooth = 0.05, maxsmooth = 0.1, curves = 7, specnum = 6)
```