spatstat (version 1.41-1)

yardstick: Text, Arrow or Scale Bar in a Diagram

Description

Create spatial objects that represent a text string, an arrow, or a yardstick (scale bar).

Usage

textstring(x, y, txt = NULL, ...)
onearrow(x0, y0, x1, y1, txt = NULL, ...)
yardstick(x0, y0, x1, y1, txt = NULL, ...)

Arguments

x,y

Coordinates where the text should be placed.

x0,y0,x1,y1

Spatial coordinates of both ends of the arrow or yardstick. Alternatively x0 can be a point pattern (class "ppp") containing exactly two points, or a line segment pattern (class "psp") consisting of exact

txt

The text to be displayed beside the line segment. Either a character string or an expression.

...

Additional named arguments for plotting the object.

Value

• An object of class "diagramobj" which also belongs to one of the special classes "textstring", "onearrow" or "yardstick". There are methods for plot, print, "[" and shift.

Details

These commands create objects that represent components of a diagram:

• textstringcreates an object that represents a string of text at a particular spatial location.
• onearrowcreates an object that represents an arrow between two locations.
• yardstickcreates an object that represents a scale bar: a line segment indicating the scale of the plot.

To display the relevant object, it should be plotted, using plot. See the help files for the plot methods plot.textstring, plot.onearrow and plot.yardstick.

These objects are designed to be included as components in a layered object or a solist. This makes it possible to build up a diagram consisting of many spatial objects, and to annotate the diagram with arrows, text and so on, so that ultimately the entire diagram is plotted using plot.

See Also

plot.textstring, plot.onearrow, plot.yardstick.

Examples

X <- rescale(swedishpines)
  plot(X, pch=16, main="")
  ys <- yardstick(as.psp(list(xmid=4, ymid=0.5, length=1, angle=0),
                         window=Window(X)),
                  txt="1 m")
  plot(ys, angle=90)