Set or Query Graphical Parameters

Description

par can be used to set or query graphical parameters. Parameters can be set by specifying them as arguments to par in tag = value form, or by passing them as a list of tagged values.

Usage

par(..., no.readonly = FALSE)

<highlevel plot> (..., <tag> = <value>)

Arguments

Details

Parameters are queried by giving one or more character vectors to par.

par() (no arguments) or par(no.readonly=TRUE) is used to get all the graphical parameters (as named list). Their names are currently taken from the variable .Pars. .Pars.readonly contains the names of the par arguments which are readonly.

R.O. Arguments := Read-only arguments: These may only be used in queries, i.e., they do not set anything.

All but these R.O. and the following low-level arguments can be set as well in high-level and mid-level plot functions, such as plot, points, lines, axis, title, text, mtext:

• "ask"
• "fig", "fin"
• "mai", "mar", "mex"
• "mfrow", "mfcol", "mfg"
• "new"
• "oma", "omd", "omi"
• "pin", "plt", "ps", "pty"
• "usr"
• "xlog", "ylog"

Value

When parameters are set, their former values are returned in an invisible named list. Such a list can be passed as an argument to par to restore the parameter values. Use par(no.readonly = TRUE) for the full list of parameters that can be restored.

When one parameter is queried, the value is a character string. When two or more parameters are queried, the result is a list of character strings, with the list names giving the parameters.

Note the inconsistency: setting one parameter returns a list, but querying one parameter returns a vector.

Color Specification

Colors can be specified in several different ways. The simplest way is with a character string giving the color name (e.g., "red"). A list of the possible colors can be obtained with the function colors. Alternatively, colors can be specified directly in terms of there RGB components with a string of the form "#RRGGBB" where each of the pairs RR, GG, BB consist of two hexadecimal digits giving a value in the range 00 to FF. Colors can also be specified by giving an index into a small table of colors. This provides compatibility with S.

The functions rgb, hsv, gray and rainbow provide additional ways of generating colors.

Line Type Specification

Line types can either be specified by giving an index into a small built in table of line types (1=solid, 2=dashed, 3=dotted) or directly as the lengths of on/off stretches of line. This is done with a string of up to eight characters which give the lengths in consecutive positions in the string. For example, the string "33" specifies three pixels on followed by three off and "3313" specifies three pixels on followed by three off followed by one on and finally three off.

See Also

plot.default for some high-level plotting parameters; colors, gray, rainbow, rgb; options for other setup parameters; graphic devices x11, postscript and setting up device regions by layout and split.screen.

Examples

op <- par(mfrow = c(2, 2), # 2 x 2 pictures on one plot
          pty = "s")      # square plotting region, independent of device size

## At end of plotting, reset to previous settings:
par(op)

## Alternatively,
op <- par(no.readonly = TRUE)# the whole list of settable par's.
## do lots of plotting and par(.) calls, then reset :
par(op)

par("ylog")# FALSE
plot(1:12,log="y")
par("ylog")# TRUE

( nr.prof <-
  c(prof.pilots=16,lawyers=11,farmers=10,salesmen=9,physicians=9,
    mechanics=6,policemen=6,managers=6,engineers=5,teachers=4,
    housewives=3,students=3,armed.forces=1))
par(las=3)
barplot(rbind(nr.prof)) # R 0.63.2: shows alignment problem
par(las=0)# reset to default

ex <- function() {
   old.par <- par(no.readonly = TRUE)# all par settings which could be changed.
   on.exit(par(old.par))
   ## ...
   ## ... do lots of par(..) settings and plots
   ## ...
   invisible() #-- now,  par(old.par)  will be executed
}
ex()