R: Contour plot of pixel image

contour.im {spatstat.geom} | R Documentation

## Contour plot of pixel image

### Description

Generates a contour plot of a pixel image.

### Usage

       ## S3 method for class 'im'
    contour(x, ..., main,
                axes=FALSE, add=FALSE, col=par("fg"),
                clipwin=NULL, show.all=!add, do.plot=TRUE)

### Arguments

`x` | Pixel image to be plotted. An object of class `"im"`.
`main` | Character string to be displayed as the main title.
`axes` | Logical. If `TRUE`, coordinate axes are plotted (with tick marks) around a region slightly larger than the image window. If `FALSE` (the default), no axes are plotted, and a box is drawn tightly around the image window. Ignored if `add=TRUE`.
`add` | Logical. If `FALSE`, a new plot is created. If `TRUE`, the contours are drawn over the existing plot.
`col` | Colour in which to draw the contour lines. Either a single value that can be interpreted as a colour value, or a `colourmap` object.
`clipwin` | Optional. A window (object of class `"owin"`). Only this subset of the data will be displayed.
`...` | Other arguments passed to `contour.default` controlling the contour plot; see Details.
`show.all` | Logical value indicating whether to display all plot elements including the main title, bounding box, and (if `axis=TRUE`) coordinate axis markings. Default is `TRUE` for new plots and `FALSE` for added plots.
`do.plot` | Logical value indicating whether to actually perform the plot.

### Details

This is a method for the generic `contour` function, for objects of the class `"im"`.

An object of class `"im"` represents a pixel image; see `im.object`.

This function displays the values of the pixel image `x` as a contour plot on the current plot device, using equal scales on the x and y axes.

The appearance of the plot can be modified using any of the arguments listed in the help for `contour.default`. Useful ones include:

nlevels

  Number of contour levels to plot.

drawlabels

  Whether to label the contour lines with text.

col,lty,lwd

  Colour, type, and width of contour lines.

See `contour.default` for a full list of these arguments.

The defaults for any of the abovementioned arguments can be reset using `spatstat.options("par.contour")`.

If `col` is a colour map (object of class `"colourmap"`, see `colourmap`) then the contours will be plotted in different colours as determined by the colour map. The contour at level `z` will be plotted in the colour `col(z)` associated with this level in the colour map.

### Value

none.

### Author(s)

Adrian Baddeley Adrian.Baddeley@curtin.edu.au

Rolf Turner r.turner@auckland.ac.nz

and Ege Rubak rubak@math.aau.dk

### See Also

`im.object`, `plot.im`, `persp.im`

### Examples

       # an image
       Z <- setcov(owin())
       contour(Z, axes=TRUE)
       contour(Z)

       co <- colourmap(rainbow(100), range=c(0,1))
       contour(Z, col=co, lwd=2)

[Package spatstat.geom version 2.2-0 Index]