gpar {grid} | R Documentation |
This function returns an object of class "gpar"
. This is
basically a list of name-value pairs.
gpar(...)
... |
Any number of named arguments. |
All grid viewports and (predefined) graphical objects have a slot
called gp
, which contains a "gpar"
object. When
a viewport is pushed onto the viewport stack and when a graphical object
is drawn, the settings in the "gpar"
object are enforced.
In this way, the graphical output is modified by the gp
settings until the graphical object has finished drawing, or until the
viewport is popped off the viewport stack, or until some other
viewport or graphical object is pushed or begins drawing.
Valid parameter names are:
col | Colour for lines and borders. |
fill | Colour for filling rectangles, polygons, ... |
lty | Line type |
lwd | Line width |
fontsize | The size of text (in points) |
fontfamily | The font family |
fontface | The font face (bold, italic, ...) |
lineheight | The height of a line as a multiple of fontsize |
font | Font face (alias for fontface; for backward compatibility) |
For most devices, the fontfamily
is specified when the device
is first opened and may not be changed thereafter i.e., specifying
a different font family via fontfamily
will be ignored. This
will hopefully change in future versions of R. Also, there is an
important exception: fontfamily
may be used to specify one
of the Hershey Font families (e.g., HersheySerif
)
and this specification will be honoured
on all devices.
The specification of fontface
follows the R base graphics
standard: 1 = plain, 2 = bold, 3 = italic, 4 = bold italic.
Specifying the value NULL
for a parameter is the same as not
specifying any value for that parameter, except for col
and
fill
, where NULL
indicates not to draw a border or
not to fill an area (respectively).
All parameter values can be vectors of multiple values. (This will not always make sense for example, viewports will only take notice of the first parameter value.)
An object of class "gpar"
.
Paul Murrell
gpar(col="red") gpar(col="blue", lty="solid", lwd=3, fontsize=16) grid.newpage() vp <- viewport(w=.8, h=.8, gp=gpar(col="blue")) grid.collection(grid.rect(gp=gpar(col="red"), draw=FALSE), grid.text("The rect is its own colour (red)\nbut this text is the colour\nset by the collection (green)", draw=FALSE), gp=gpar(col="green"), vp=vp) grid.text("This text is the colour set by the viewport (blue)", y=1, just=c("center", "bottom"), gp=gpar(fontsize=20), vp=vp) grid.newpage() # example with multiple values for a parameter grid.points(1:10/11, 1:10/11, gp=gpar(col=1:10))