Graphics Reference
In-Depth Information
Figure
.
.
Basic scatterplot with extra rectangles, lines, polygons and text added to it
Some slightly more complex primitives (not currently natively supported by R)are
spline curves, arbitrary paths (as in PostScript or SVG) and polygons with holes,
which are useful for drawing maps. An example of a polygon with a hole is an is-
land within a lake within an island, where both islands are part of the same country
or state and so are usefully represented as a single polygon.
Coordinate Systems
One of the most important and distinctive features of statistical graphics sotware is
that it is not only capable of producing many pieces of graphical output at once (lots
of lines, text, and symbols that together make up a plot), but that it is also capable of
positioning the graphical output within more than one coordinate system. Here are
some examples (Fig.
.
):
he title of a plot might be positioned halfway across a page. hat is, the title is
positionedrelativetoa'normalized'coordinatesystemthatcoverstheentirepage,
where the location
corresponds to the let edge of the page and the location
corresponds to the right edge.
he data symbols in a scatterplot are positioned relative to a coordinate system
corresponding to the range of the data that only covers the area of the page
bounded by the plot axes.
he axis labels might be positioned halfway along an axis. hat is, the axis labels
are positioned relative to a 'normalized' coordinate system that only covers the
areaofthepageboundedbytheplotaxes.
