geom_maskarea: Mask all area outside of saturation line
In hongyuanjia/ggpsychro: A 'ggplot2' Extension for Making Pyschrometric Charts

Description Usage Arguments Details Aesthetics Examples

geom_maskarea() draws a polygon to mask all area outside of the saturation line. The vertices of polygon are based on current psychrometric chart's dry-bulb temperature (x axis) range and humidity ratio (y axis) range.

geom_maskarea(
  mapping = NULL,
  data = NULL,
  units = waiver(),
  pres = waiver(),
  n = 201,
  ...,
  na.rm = FALSE
)

`mapping`	Set of aesthetic mappings created by `aes()` or `aes_()`. If specified and `inherit.aes = TRUE` (the default), it is combined with the default mapping at the top level of the plot. You must supply `mapping` if there is no plot mapping.
`data`	The data to be displayed in this layer. There are three options: If `NULL`, the default, the data is inherited from the plot data as specified in the call to `ggplot()`. A `data.frame`, or other object, will override the plot data. All objects will be fortified to produce a data frame. See `fortify()` for which variables will be created. A `function` will be called with a single argument, the plot data. The return value must be a `data.frame`, and will be used as the layer data. A `function` can be created from a `formula` (e.g. `~ head(.x, 10)`).
`units`	A single string indicating the units sytem to use. Should be either `"SI"` or `"IP" or` waiver()`which uses the value from the parent plot. Default:`waiver()'.
`pres`	A single number indicating the atmosphere pressure in Pa [SI] or Psi [IP]. If `waiver()`, the pressure calculated from the parent plot's altitude value will be used. Default: `waiver()`.
`n`	Number of points to interpolate along
`...`	Other arguments passed on to `layer()`. These are often aesthetics, used to set an aesthetic to a fixed value, like `colour = "red"` or `size = 3`. They may also be parameters to the paired geom/stat.
`na.rm`	If `FALSE`, the default, missing values are removed with a warning. If `TRUE`, missing values are silently removed.

geom_maskarea() is based on ggplot2::geom_polygon(), so you can further customize the area style in the same way.

Normally there is no need to add another mask since ggpsychro() calls geom_maskarea() internally and makes sure that it is always rendered after other layers.

geom_maskarea() understands the following aesthetics (required aesthetics are in bold).

color
size
linetype

# by default, a mask is automatically added when calling 'ggpsychro()' function
ggpsychro()

# replace with another mask area for pressure at 102000
ggpsychro() +
    geom_maskarea(units = "SI", pres = 102000)

# the line style can be further customized like 'ggplot2::geom_line()'
ggpsychro() +
    geom_maskarea(units = "SI", pres = 101325, color = "blue", fill = "green")