Graphics with R University of Michigan（图形与R 密歇根大学）.pdf

Graphics with R R Development Core Group R-core@R-project.org Graphics with R – p Graphical capabilities One of the strengths of the S language is graphics. Simple, exploratory graphics are easy to produce. Publication quality graphics can be created. Several device drivers are available including: On-screen graphics - either Windows, or X11, or Macintosh postscript - PostScript graphics commands pdf - Adobe Portable Document Format png - PNG bitmap device (like .gif but free of software patents) jpeg - JPEG bitmap WMF - Windows meta-file (Windows only) Graphics with R – p Declaring graphics devices The on-screen devices are the most commonly used. For publication-quality graphics the postscript, pdf, or WMF devices are preferred because they produce scalable images. Use bitmap devices only when there is no alternative. The preferred sequence is to specify a graphics device then call graphics functions. If you do not specify a device first, the on-screen device is started. A contributed R package called lattice provides Trellis graphics functions. When using lattice it is important to declare the device using trellis.device before issuing graphics commands. Graphics with R – p Types of graphics functions High-level - functions such as plot, hist, boxplot, or pairs that produce an entire plot or initialize a plot. low-level - functions that add to an existing plot created with a high-level plotting function. Examples are points, lines, text, axis, Trellis functions - functions such as xyplot, bwplot, or histogram that can pro