R: Plot a Spatial Window

plot.owin {spatstat} | R Documentation

## Plot a Spatial Window

### Description

Plot a two-dimensional window of observation for a spatial point pattern

### Usage

     ## S3 method for class 'owin'
    plot(x, main, add=FALSE, ..., box, edge=0.04,
                          type=c("w","n"), show.all=!add,
                          hatch=FALSE,
                          hatchargs=list(),
                          invert=FALSE, do.plot=TRUE,
                          claim.title.space=FALSE)

### Arguments

`x` | The window to be plotted. An object of class `owin`, or data which can be converted into this format by `as.owin()`.
`main` | text to be displayed as a title above the plot.
`add` | logical flag: if `TRUE`, draw the window in the current plot; if `FALSE`, generate a new plot.
`...` | extra arguments controlling the appearance of the plot. These arguments are passed to `polygon` if `x` is a polygonal or rectangular window, or passed to `image.default` if `x` is a binary mask. See Details.
`box` | logical flag; if `TRUE`, plot the enclosing rectangular box
`edge` | nonnegative number; the plotting region will have coordinate limits that are `1 + edge` times as large as the limits of the rectangular box that encloses the pattern.
`type` | Type of plot: either `"w"` or `"n"`. If `type="w"` (the default), the window is plotted. If `type="n"` and `add=TRUE`, a new plot is initialised and the coordinate system is established, but nothing is drawn.
`show.all` | Logical value indicating whether to plot everything including the main title.
`hatch` | logical flag; if `TRUE`, the interior of the window will be shaded by texture, such as a grid of parallel lines.
`hatchargs` | List of arguments passed to `add.texture` to control the texture shading when `hatch=TRUE`.
`invert` | logical flag; when the window is a binary pixel mask, the mask colours will be inverted if `invert=TRUE`.
`do.plot` | Logical value indicating whether to actually perform the plot.
`claim.title.space` | Logical value indicating whether extra space for the main title should be allocated when declaring the plot dimensions. Should be set to `FALSE` under normal conditions.

### Details

This is the `plot` method for the class `owin`. The action is to plot the boundary of the window on the current plot device, using equal scales on the `x` and `y` axes.

If the window `x` is of type `"rectangle"` or `"polygonal"`, the boundary of the window is plotted as a polygon or series of polygons. If `x` is of type `"mask"` the discrete raster approximation of the window is displayed as a binary image (white inside the window, black outside).

Graphical parameters controlling the display (e.g. setting the colours) may be passed directly via the `...` arguments, or indirectly reset using `spatstat.options`.

When `x` is of type `"rectangle"` or `"polygonal"`, it is plotted by the R function `polygon`. To control the appearance (colour, fill density, line density etc) of the polygon plot, determine the required argument of `polygon` and pass it through `...` For example, to paint the interior of the polygon in red, use the argument `col="red"`. To draw the polygon edges in green, use `border="green"`. To suppress the drawing of polygon edges, use `border=NA`.

When `x` is of type `"mask"`, it is plotted by `image.default`. The appearance of the image plot can be controlled by passing arguments to `image.default` through `...`. The default appearance can also be changed by setting the parameter `par.binary` of `spatstat.options`.

To zoom in (to view only a subset of the window at higher magnification), use the graphical arguments `xlim` and `ylim` to specify the desired rectangular field of view. (The actual field of view may be larger, depending on the graphics device).

### Value

none.

### Notes on Filled Polygons with Holes

The function `polygon` can only handle polygons without holes. To plot polygons with holes in a solid colour, we have implemented two workarounds.

polypath function:

  The first workaround uses the relatively new function `polypath` which does have the capability to handle polygons with holes. However, not all graphics devices support `polypath`. The older devices `xfig` and `pictex` do not support `polypath`. On a Windows system, the default graphics device `windows` supports `polypath`.

polygon decomposition:

  The other workaround involves decomposing the polygonal window into pieces which do not have holes. This code is experimental but works in all our test cases. If this code fails, a warning will be issued, and the filled colours will not be plotted.

### Author(s)

Adrian Baddeley Adrian.Baddeley@curtin.edu.au

and Rolf Turner r.turner@auckland.ac.nz

### See Also

`owin.object`, `plot.ppp`, `polygon`, `image.default`, `spatstat.options`

### Examples

      # rectangular window
       plot(Window(nztrees))
       abline(v=148, lty=2)

      # polygonal window
      w <- Window(demopat)
      plot(w)
      plot(w, col="red", border="green", lwd=2)
      plot(w, hatch=TRUE, lwd=2)

      # binary mask
      we <- as.mask(w)
      plot(we)
      op <- spatstat.options(par.binary=list(col=grey(c(0.5,1))))
      plot(we)
      spatstat.options(op)

[Package spatstat version 1.54-0 Index]