| axis {graphics} | R Documentation |
Adds an axis to the current plot, allowing the specification of the side, position, labels, and other options.
axis(side, at = NULL, labels = TRUE, tick = TRUE, line = NA,
pos = NA, outer = FALSE, font = NA, vfont = NULL,
lty = "solid", lwd = 1, col = NULL, ...)
side |
an integer specifying which side of the plot the axis is to be drawn on. The axis is placed as follows: 1=below, 2=left, 3=above and 4=right. |
at |
the points at which tick-marks are to be drawn. Non-finite
(infinite, NaN or NA) values are omitted. By default,
when NULL, tickmark locations are computed, see Details below. |
labels |
this can either be a logical value specifying whether (numerical) annotations are to be made at the tickmarks, or a vector of character strings to be placed at the tickpoints. |
tick |
a logical value specifying whether tickmarks should be drawn |
line |
the number of lines into the margin which the axis will
be drawn. This overrides the value of the graphical parameter
mgp[3]. The relative placing of tickmarks and tick labels
is unchanged. |
pos |
the coordinate at which the axis line is to be drawn:
this overrides the values of both line and mgp[3]. |
outer |
a logical value indicating whether the axis should be drawn in the outer plot margin, rather than the standard plot margin. |
font |
font for text. |
vfont |
vector font for text. |
lty, lwd |
line type, width for the axis line and the tick marks. |
col |
color for the axis line and the tick marks. The default
NULL means to use par("fg"). |
... |
other graphical parameters may also be passed as arguments to
this function, particularly, cex.axis, col.axis and
font.axis for axis annotation, las for
vertical/horizontal label orientation, or fg instead of
col, see par on these. |
The axis line is drawn from the lowest to the highest value of
at, but will be clipped at the plot region. Only ticks which
are drawn from points within the plot region (up to a tolerance for
rounding error) are plotted, but the ticks and their labels may well
extend outside the plot region.
When at = NULL, pretty tick mark locations are computed internally
(the same way axTicks(side) would) from
par("usr", "lab") and par("xlog") (or
"ylog").
Several of the graphics parameters affect the way axes are drawn. The
vertical (for sides 1 and 3) positions of the axis and the tick labels
are controlled by mgp, the size of the ticks is controlled by
tck and tcl and the appearance of the tick labels by
cex.axis, col.axis and font.axis with
orientation controlled by las (but not srt, unlike S
which uses srt if at is supplied and las if it is
not).
This function is invoked for its side effect, which is to add an axis to an already existing plot.
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
axTicks returns the axis tick locations
corresponding to at=NULL; pretty is more flexible
for computing pretty tick coordinates and does not depend on
(nor adapt to) the coordinate system in use.
plot(1:4, rnorm(4), axes=FALSE)
axis(1, 1:4, LETTERS[1:4])
axis(2)
box() #- to make it look "as usual"
plot(1:7, rnorm(7), main = "axis() examples",
type = "s", xaxt = "n", frame = FALSE, col = "red")
axis(1, 1:7, LETTERS[1:7], col.axis = "blue")
# unusual options:
axis(4, col = "violet", col.axis="dark violet", lwd = 2)
axis(3, col = "gold", lty = 2, lwd = 0.5)