R Graphics Reference

Note that, like PostScript, the origin is the bottom left corner of the display area (the cyan box), and that the y co-ordinates count up from the bottom. This is true of the R standard graphics as well as the PostScript style graphics.

There are three sections to this reference:

• PostScript style graphics engine: a set of functions similar to the PostScript graphics functions
• R standard graphics: a different set of functions for drawing particular shapes.
• Property setters of the user space co-ordinate system and the graphics output window. These functions are used for both sets of graphics.

PostScript style graphics (function prefix #ps)

• #ps.newpath: Starts a new path, wiping the current path and subpath.
• #ps.closepath: Closes the current subpath by returning the current point to the start of it.
• nx ny #ps.moveto: Sets the current point to nx, ny, and starts a new subpath.
• nx ny #ps.rmoveto: Moves the current point nx, ny pixels up and across,
• nx ny #ps.lineto: Draws a line from the current point to nx, ny, then moves it.
• nx ny #ps.rlineto: Draws a line from the current point to nx, ny pixels above and to the right of it, then moves it.
• #ps.currentpoint: Puts the current point (in user space) onto the stack as two numeric scalars, the x and y co-ordinates.
• #ps.stroke: Outlines the current path, then starts a new one. To keep the current path, e.g. if you want to fill the same path, use the sequence #ps.gsave #ps.stroke #ps.grestore.
• #ps.fill: Closes and fills all subpaths on the current path, including the current subpath. #ps.fill then starts a new path – to keep the current path, e.g. if you want to outline the same path, use the sequence #ps.gsave #ps.fill #ps.grestore.
• #ps.fillsubpath: Fills the current subpath, starting a new subpath.
• cv #ps.show: Shows the text cv in the current font at the current point.
• #ps.showpage: Displays the graphics window.
• #ps.gsave: Saves the current graphics state on the graphics stack.
• #ps.grestore: Restores the graphics state on top of the graphics stack.

R standard graphics (function prefix #g)

• n1 n2 n3 n4 #g.line: Draws a line from n1, n2 to n3, n4.
• n1 n2 n3 n4 #g.rect: Draws a rectangle between n1, n2 and n3, n4.
• n1 n2 n3 n4 #g.frect: Draws a rectangle between n1, n2 and n3, n4, then fills it.
• nv #g.pline: Draws a polyline using nv as a list of x, y, ... etc. pairs.
• nv #g.fpoly: Fills a polygon using nv as a list of x, y, ... etc. pairs.
• nv #g.ptick: Draws a polytick set using nv as a list of x, y, x, y ... etc. fours.
• nv #g.prect: Draws a polyrect set using nv as a list of x, y, x, y ... etc. fours.
• nv #g.fprect: Fills a polyrect set using nv as a list of x, y, x, y ... etc. fours.
• #g.display: Displays the graphics window.

Property setters and generic functions

• nx ny #ps.setdisplaysize or #g.setdisplaysize: Resizes the graphics display so it can accommodate nx by ny points, on the current pixels-per-point conversion ratio (see #ps.setppt).
• #ps.getdisplaysize or #g.getdisplaysize: Puts the current window size, in points, onto the stack as two numeric scalars.
• n #ps.setppt or #g.setppt (not implemented yet!): Sets the pixels-per-point ratio to be n pixels to 1 point. This defaults to 1.
• #ps.getppt or #g.getppt (not implemented yet!): Returns the current pixels-per-point ratio.
• nx ny #ps.scale or #g.scale: Scales the co-ordinate system.
• nx ny #ps.translate or #g.translate: Moves the co-ordinate system.
• n #ps.rotate or #g.rotate: Rotates the co-ordinate system through n degrees anti-clockwise.
  Note that text is not rotated.
• #ps.resetctm or #g.resetctm: Resets the co-ordinate system.
• #ps.reset or #g.reset: Blanks the graphics display and resets graphics variables.
• nr ng nb #ps.setrgbcolour or #g.setcolour: Sets the current colour to have RGB content (nr, ng, nb).
• nh ns nb #ps.sethsbcolour or #g.sethsbcolour: Sets the current colour to have HSB (hue, saturation, brightness) content (nh, ns, nb).
• n #ps.setgrey or #g.setgrey: Sets the current colour to have RGB content of 255*n.
• n1 n2 n3 #ps.setfont or #g.setfont: Sets the current font to be font n1, size n2, and style n3 from Plain, Italic, Bold or BoldItalic (0, 1, 2, or 3).
  The font faces are:
  1. Times
  2. Helvetica/Arial
  3. Courier
  4. "Dialog"
  5. Symbol

Page and site © Richard Smith 2001
Please send any comments to richard@redcorona.com - thank you.