par | R Documentation |
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.
par(..., no.readonly = FALSE) <highlevel plot> (..., <tag> = <value>)
... |
arguments in |
no.readonly |
logical; if |
Each device has its own set of graphical parameters. If the current
device is the null device, par
will open a new device before
querying/setting parameters. (What device is controlled by
options("device")
.)
Parameters are queried by giving one or more character vectors of
parameter names to par
.
par()
(no arguments) or par(no.readonly = TRUE)
is used to
get all the graphical parameters (as a named list). Their
names are currently taken from the unexported variable
graphics:::.Pars
.
R.O. indicates read-only arguments: These
may only be used in queries and cannot be set. ("cin"
,
"cra"
, "csi"
, "cxy"
, "din"
and
"page"
are always read-only.)
Several parameters can only be set by a call to par()
:
"ask"
,
"fig"
, "fin"
,
"lheight"
,
"mai"
, "mar"
, "mex"
,
"mfcol"
, "mfrow"
, "mfg"
,
"new"
,
"oma"
, "omd"
, "omi"
,
"pin"
, "plt"
, "ps"
, "pty"
,
"usr"
,
"xlog"
, "ylog"
,
"ylbias"
The remaining parameters can also be set as arguments (often via
...
) to high-level plot functions such as
plot.default
, plot.window
,
points
, lines
, abline
,
axis
, title
, text
,
mtext
, segments
, symbols
,
arrows
, polygon
, rect
,
box
, contour
, filled.contour
and image
. Such settings will be active during the
execution of the function, only. However, see the comments on
bg
, cex
, col
, lty
, lwd
and
pch
which may be taken as arguments to certain plot
functions rather than as graphical parameters.
The meaning of ‘character size’ is not well-defined: this is
set up for the device taking pointsize
into account but often
not the actual font family in use. Internally the corresponding pars
(cra
, cin
, cxy
and csi
) are used only to
set the inter-line spacing used to convert mar
and oma
to physical margins. (The same inter-line spacing multiplied by
lheight
is used for multi-line strings in text
and
strheight
.)
Note that graphical parameters are suggestions: plotting functions and
devices need not make use of them (and this is particularly true of
non-default methods for e.g. plot
).
When parameters are set, their previous 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.
However, restoring all of these is not wise: see the ‘Note’
section.
When just one parameter is queried, the value of that parameter is returned as (atomic) vector. When two or more parameters are queried, their values are returned in a list, with the list names giving the parameters.
Note the inconsistency: setting one parameter returns a list, but querying one parameter returns a vector.
adj
The value of adj
determines the way in
which text strings are justified in text
,
mtext
and title
. A value of 0
produces
left-justified text, 0.5
(the default) centered text and 1
right-justified text. (Any value in [0, 1] is allowed, and
on most devices values outside that interval will also work.)
Note that the adj
argument of text
also
allows adj = c(x, y)
for different adjustment in x- and y-
directions. Note that whereas for text
it refers to
positioning of text about a point, for mtext
and
title
it controls placement within the plot or device region.
ann
If set to FALSE
, high-level plotting
functions calling plot.default
do not annotate the
plots they produce with axis titles and overall titles. The
default is to do annotation.
ask
logical. If TRUE
(and the R session is
interactive) the user is asked for input, before a new figure is
drawn. As this applies to the device, it also affects output by
packages grid and lattice. It can be set even on
non-screen devices but may have no effect there.
This not really a graphics parameter, and its use is deprecated in
favour of devAskNewPage
.
bg
The color to be used for the background of the
device region. When called from par()
it also sets
new = FALSE
. See section ‘Color Specification’ for
suitable values. For many devices the initial value is set from
the bg
argument of the device, and for the rest it is
normally "white"
.
Note that some graphics functions such as
plot.default
and points
have an
argument of this name with a different meaning.
bty
A character string which determined the type of
box
which is drawn about plots. If bty
is
one of "o"
(the default), "l"
, "7"
,
"c"
, "u"
, or "]"
the resulting box resembles
the corresponding upper case letter. A value of "n"
suppresses the box.
cex
A numerical value giving the amount by which
plotting text and symbols should be magnified relative to the
default. This starts as 1
when a device is opened, and is
reset when the layout is changed, e.g. by setting mfrow
.
Note that some graphics functions such as
plot.default
have an argument of this name
which multiplies this graphical parameter, and some
functions such as points
and text
accept a vector of values which are recycled.
cex.axis
The magnification to be used for axis
annotation relative to the current setting of cex
.
cex.lab
The magnification to be used for x and y
labels relative to the current setting of cex
.
cex.main
The magnification to be used for main titles
relative to the current setting of cex
.
cex.sub
The magnification to be used for sub-titles
relative to the current setting of cex
.
cin
R.O.; character size
(width, height)
in inches. These are the same measurements
as cra
, expressed in different units.
col
A specification for the default plotting color. See section ‘Color Specification’.
Some functions such as lines
and text
accept a vector of values which are recycled and may be
interpreted slightly differently.
col.axis
The color to be used for axis
annotation. Defaults to "black"
.
col.lab
The color to be used for x and y labels.
Defaults to "black"
.
col.main
The color to be used for plot main titles.
Defaults to "black"
.
col.sub
The color to be used for plot sub-titles.
Defaults to "black"
.
cra
R.O.; size of default character
(width, height)
in ‘rasters’ (pixels). Some devices
have no concept of pixels and so assume an arbitrary pixel size,
usually 1/72 inch. These are the same measurements
as cin
, expressed in different units.
crt
A numerical value specifying (in degrees) how
single characters should be rotated. It is unwise to expect
values other than multiples of 90 to work. Compare with
srt
which does string rotation.
csi
R.O.; height of (default-sized)
characters in inches. The same as par("cin")[2]
.
cxy
R.O.; size of default character
(width, height)
in user coordinate units.
par("cxy")
is par("cin")/par("pin")
scaled to user
coordinates.
Note that c(strwidth(ch), strheight(ch))
for
a given string ch
is usually much more precise.
din
R.O.; the device dimensions,
(width, height)
, in inches. See also
dev.size
, which is updated immediately when an
on-screen device windows is re-sized.
err
(Unimplemented; R is silent when points outside the plot region are not plotted.) The degree of error reporting desired.
family
The name of a font family for drawing text.
The maximum allowed length is 200 bytes.
This name gets mapped by each graphics device to a device-specific
font description. The default value is ""
which means that
the default device fonts will be used (and what those are should
be listed on the help page for the device). Standard values are
"serif"
, "sans"
and "mono"
, and the
Hershey font families are also available. (Devices may
define others, and some devices will ignore this setting
completely. Names starting with "Hershey"
are treated
specially and should only be used for the built-in Hershey font
families.) This can be specified inline for text
.
fg
The color to be used for the foreground of plots.
This is the default color used for things like axes and boxes
around plots. When called from par()
this also sets
parameter col
to the same value. See section ‘Color
Specification’. A few devices have an argument to set the
initial value, which is otherwise "black"
.
fig
A numerical vector of the form c(x1, x2, y1,
y2)
which gives the (NDC) coordinates of the figure region in
the display region of the device. If you set this, unlike S, you
start a new plot, so to add to an existing plot use
new = TRUE
as well.
fin
The figure region dimensions,
(width, height)
, in inches. If you set this, unlike S, you
start a new plot.
font
An integer which specifies which font to use for
text. If possible, device drivers arrange so that 1 corresponds
to plain text (the default), 2 to bold face, 3 to italic and 4 to
bold italic. Also, font 5 is expected to be the symbol font, in
Adobe symbol encoding. On some devices font families can be
selected by family
to choose different sets of 5 fonts.
font.axis
The font to be used for axis annotation.
font.lab
The font to be used for x and y labels.
font.main
The font to be used for plot main titles.
font.sub
The font to be used for plot sub-titles.
lab
A numerical vector of the form c(x, y, len)
which modifies the default way that axes are annotated. The values of
x
and y
give the (approximate) number of tickmarks
on the x and y axes and len
specifies the label length. The
default is c(5, 5, 7)
. Note that this only affects the way
the parameters xaxp
and yaxp
are set when the user
coordinate system is set up, and is not consulted when axes are drawn.
len
is unimplemented in R.
las
numeric in {0,1,2,3}; the style of axis labels.
always parallel to the axis [default],
always horizontal,
always perpendicular to the axis,
always vertical.
Also supported by mtext
. Note that
string/character rotation via argument srt
to par
does not affect the axis labels.
lend
The line end style. This can be specified as an integer or string:
0
and "round"
mean rounded line caps
[default];
1
and "butt"
mean butt line caps;
2
and "square"
mean square line caps.
lheight
The line height multiplier.
The height of a line of text (used to vertically space
multi-line text) is found by multiplying the character height
both by the current character expansion and by the
line height multiplier. Default value is 1. Used in
text
and strheight
.
ljoin
The line join style. This can be specified as an integer or string:
0
and "round"
mean rounded line joins
[default];
1
and "mitre"
mean mitred line joins;
2
and "bevel"
mean bevelled line joins.
lmitre
The line mitre limit. This controls when mitred line joins are automatically converted into bevelled line joins. The value must be larger than 1 and the default is 10. Not all devices will honour this setting.
lty
The line type.
Line types can either be specified as an integer (0=blank, 1=solid
(default), 2=dashed, 3=dotted, 4=dotdash, 5=longdash, 6=twodash)
or as one of the character strings "blank"
, "solid"
,
"dashed"
, "dotted"
, "dotdash"
,
"longdash"
, or "twodash"
, where "blank"
uses
‘invisible lines’ (i.e., does not draw them).
Alternatively, a string of up to 8 characters (from c(1:9,
"A":"F")
) may be given, giving the length of line segments
which are alternatively drawn and skipped. See section
‘Line Type Specification’.
Functions such as lines
and segments
accept a vector of values which are recycled.
lwd
The line width, a positive number,
defaulting to 1
. The interpretation is device-specific,
and some devices do not implement line widths less than one.
(See the help on the device for details of the interpretation.)
Functions such as lines
and segments
accept a vector of values which are recycled: in such uses lines
corresponding to values NA
or NaN
are omitted. The
interpretation of 0
is device-specific.
mai
A numerical vector of the form c(bottom,
left, top, right)
which gives the margin size specified in
inches.
mar
A numerical vector of the form c(bottom,
left, top, right)
which gives the number of lines of margin to be
specified on the four sides of the plot.
The default is c(5, 4, 4, 2) 0.1
.
mex
mex
is a character size expansion factor which is used to
describe coordinates in the margins of plots. Note that this does
not change the font size, rather specifies the size of font (as a
multiple of csi
) used to convert between mar
and
mai
, and between oma
and omi
.
This starts as 1
when the device is opened, and is reset
when the layout is changed (alongside resetting cex
).
mfcol, mfrow
A vector of the form c(nr, nc)
.
Subsequent figures will be drawn in an nr
-by-nc
array on the device by columns (mfcol
), or
rows (mfrow
), respectively.
In a layout with exactly two rows and columns the base value of
"cex"
is reduced by a factor of 0.83: if there are three or
more of either rows or columns, the reduction factor is 0.66.
Setting a layout resets the base value of cex
and that of
mex
to 1
.
If either of these is queried it will give the current layout, so querying cannot tell you the order in which the array will be filled.
Consider the alternatives, layout
and
split.screen
.
mfg
A numerical vector of the form c(i, j)
where i
and j
indicate which figure in an array of
figures is to be drawn next (if setting) or is being drawn (if
enquiring). The array must already have been set by mfcol
or mfrow
.
For compatibility with S, the form c(i, j, nr, nc)
is also
accepted, when nr
and nc
should be the current
number of rows and number of columns. Mismatches will be ignored,
with a warning.
mgp
The margin line (in mex
units) for the axis
title, axis labels and axis line. Note that mgp[1]
affects
title
whereas mgp[2:3]
affect axis
.
The default is c(3, 1, 0)
.
mkh
The height in inches of symbols to be drawn when
the value of pch
is an integer. Completely ignored in R.
new
logical, defaulting to FALSE
. If set to
TRUE
, the next high-level plotting command (actually
plot.new
) should not clean the frame before
drawing as if it were on a new device. It is
an error (ignored with a warning) to try to use new = TRUE
on a device that does not currently contain a high-level plot.
oma
A vector of the form c(bottom, left, top,
right)
giving the size of the outer margins in lines of text.
omd
A vector of the form c(x1, x2, y1, y2)
giving the region inside outer margins in NDC (=
normalized device coordinates), i.e., as a fraction (in [0, 1])
of the device region.
omi
A vector of the form c(bottom, left, top,
right)
giving the size of the outer margins in inches.
page
R.O.; A boolean value indicating
whether the next call to plot.new
is going
to start a new page. This value may be FALSE
if there
are multiple figures on the page.
pch
Either an integer specifying a symbol or a single
character to be used as the default in plotting points. See
points
for possible values and their interpretation.
Note that only integers and single-character strings can
be set as a graphics parameter (and not NA
nor NULL
).
Some functions such as points
accept a vector of values
which are recycled.
pin
The current plot dimensions, (width, height)
,
in inches.
plt
A vector of the form c(x1, x2, y1, y2)
giving the coordinates of the plot region as fractions of the
current figure region.
ps
integer; the point size of text (but not symbols). Unlike
the pointsize
argument of most devices, this does not change
the relationship between mar
and mai
(nor oma
and omi
).
What is meant by ‘point size’ is device-specific, but most devices mean a multiple of 1bp, that is 1/72 of an inch.
pty
A character specifying the type of plot region to
be used; "s"
generates a square plotting region and
"m"
generates the maximal plotting region.
smo
(Unimplemented) a value which indicates how smooth circles and circular arcs should be.
srt
The string rotation in degrees. See the comment
about crt
. Only supported by text
.
tck
The length of tick marks as a fraction of the
smaller of the width or height of the plotting region.
If tck >= 0.5
it is interpreted as a fraction of the
relevant side, so if tck = 1
grid lines are drawn. The
default setting (tck = NA
) is to use tcl = -0.5
.
tcl
The length of tick marks as a fraction of the
height of a line of text. The default value is -0.5
;
setting tcl = NA
sets tck = -0.01
which is S' default.
usr
A vector of the form c(x1, x2, y1, y2)
giving the extremes of the user coordinates of the plotting
region. When a logarithmic scale is in use (i.e.,
par("xlog")
is true, see below), then the x-limits will be
10 ^ par("usr")[1:2]
. Similarly for the y-axis.
xaxp
A vector of the form c(x1, x2, n)
giving
the coordinates of the extreme tick marks and the number of
intervals between tick-marks when par("xlog")
is false.
Otherwise, when log coordinates are active, the three
values have a different meaning: For a small range, n
is
negative, and the ticks are as in the linear case,
otherwise, n
is in 1:3
, specifying a case number,
and x1
and x2
are the lowest and highest power of 10
inside the user coordinates, 10 ^ par("usr")[1:2]
. (The
"usr"
coordinates are log10-transformed here!)
will produce tick marks at 10^j for integer j,
gives marks k 10^j with k in {1,5},
gives marks k 10^j with k in {1,2,5}.
See axTicks()
for a pure R implementation of this.
This parameter is reset when a user coordinate system is set up,
for example by starting a new page or by calling
plot.window
or setting par("usr")
: n
is taken from par("lab")
. It affects the default behaviour
of subsequent calls to axis
for sides 1 or 3.
It is only relevant to default numeric axis systems, and not for example to dates.
xaxs
The style of axis interval calculation to be used
for the x-axis. Possible values are "r"
, "i"
,
"e"
, "s"
, "d"
. The styles are generally
controlled by the range of data or xlim
, if given.
Style "r"
(regular) first extends the data range by 4
percent at each end and then finds an axis with pretty labels
that fits within the extended range.
Style "i"
(internal) just finds an axis with pretty labels
that fits within the original data range.
Style "s"
(standard) finds an axis with pretty labels
within which the original data range fits.
Style "e"
(extended) is like style "s"
, except that
it is also ensures that there is room for plotting symbols within
the bounding box.
Style "d"
(direct) specifies that the current axis should
be used on subsequent plots.
(Only "r"
and "i"
styles have been
implemented in R.)
xaxt
A character which specifies the x axis type.
Specifying "n"
suppresses plotting of the axis. The
standard value is "s"
: for compatibility with S values
"l"
and "t"
are accepted but are equivalent to
"s"
: any value other than "n"
implies plotting.
xlog
A logical value (see log
in
plot.default
). If TRUE
, a logarithmic scale
is in use (e.g., after plot(*, log = "x")
).
For a new device, it defaults to FALSE
, i.e., linear scale.
xpd
A logical value or NA
.
If FALSE
, all plotting is clipped to the plot region, if
TRUE
, all plotting is clipped to the figure region, and if
NA
, all plotting is clipped to the device region. See also
clip
.
yaxp
A vector of the form c(y1, y2, n)
giving
the coordinates of the extreme tick marks and the number of
intervals between tick-marks unless for log coordinates, see
xaxp
above.
yaxs
The style of axis interval calculation to be used
for the y-axis. See xaxs
above.
yaxt
A character which specifies the y axis type.
Specifying "n"
suppresses plotting.
ylbias
A positive real value used in the positioning
of text in the margins by axis
and
mtext
. The default is in principle device-specific,
but currently 0.2
for all of R's own devices. Set this to
0.2
for compatibility with R < 2.14.0 on x11
and
windows()
devices.
ylog
A logical value; see xlog
above.
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 their 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, the palette
:
indices wrap round so with the default palette of size 8, 10
is
the same as 2
. This provides compatibility with S. Index
0
corresponds to the background color. Note that the palette
(apart from 0
which is per-device) is a per-session setting.
Negative integer colours are errors.
Additionally, "transparent"
is transparent, useful for
filled areas (such as the background!), and just invisible for things
like lines or text. In most circumstances (integer) NA
is equivalent to "transparent"
(but not for
text
and mtext
).
Semi-transparent colors are available for use on devices that support them.
The functions rgb
, hsv
, hcl
,
gray
and rainbow
provide additional ways
of generating colors.
Line types can either be specified by giving an index into a small
built-in table of line types (1 = solid, 2 = dashed, etc, see
lty
above) or directly as the lengths of on/off stretches of
line. This is done with a string of an even number (up to eight)
of characters, namely non-zero
(hexadecimal) digits which give the lengths in consecutive positions
in the string. For example, the string "33"
specifies three
units on followed by three off and "3313"
specifies three units
on followed by three off followed by one on and finally three off.
The ‘units’ here are (on most devices) proportional to
lwd
, and with lwd = 1
are in pixels or points or 1/96
inch.
The five standard dash-dot line types (lty = 2:6
) correspond to
c("44", "13", "1343", "73", "2262")
.
Note that NA
is not a valid value for lty
.
The effect of restoring all the (settable) graphics parameters as
in the examples is hard to predict if the device has been resized.
Several of them are attempting to set the same things in different
ways, and those last in the alphabet will win. In particular, the
settings of mai
, mar
, pin
, plt
and
pty
interact, as do the outer margin settings, the figure
layout and figure region size.
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
Murrell, P. (2005) R Graphics. Chapman & Hall/CRC Press.
plot.default
for some high-level plotting parameters;
colors
; clip
;
options
for other setup parameters;
graphic devices x11
, postscript
and
setting up device regions by layout
and
split.screen
.
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) ## Note this is not in general good practice par("ylog") # FALSE plot(1 : 12, log = "y") par("ylog") # TRUE plot(1:2, xaxs = "i") # 'inner axis' w/o extra space par(c("usr", "xaxp")) ( 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 require(grDevices) # for gray ## 'fg' use: plot(1:12, type = "b", main = "'fg' : axes, ticks and box in gray", fg = gray(0.7), bty = "7" , sub = R.version.string) 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() ## Line types showLty <- function(ltys, xoff = 0, ...) { stopifnot((n <- length(ltys)) >= 1) op <- par(mar = rep(.5,4)); on.exit(par(op)) plot(0:1, 0:1, type = "n", axes = FALSE, ann = FALSE) y <- (n:1)/(n 1) clty <- as.character(ltys) mytext <- function(x, y, txt) text(x, y, txt, adj = c(0, -.3), cex = 0.8, ...) abline(h = y, lty = ltys, ...); mytext(xoff, y, clty) y <- y - 1/(3*(n 1)) abline(h = y, lty = ltys, lwd = 2, ...) mytext(1/8 xoff, y, paste(clty," lwd = 2")) } showLty(c("solid", "dashed", "dotted", "dotdash", "longdash", "twodash")) par(new = TRUE) # the same: showLty(c("solid", "44", "13", "1343", "73", "2262"), xoff = .2, col = 2) showLty(c("11", "22", "33", "44", "12", "13", "14", "21", "31"))
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