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bxp draws box plots based on the given summaries in z.
It is usually called from within boxplot, but can be
invoked directly.
bxp(z, notch = FALSE, width = NULL, varwidth = FALSE,
outline = TRUE, notch.frac = 0.5, log = "",
border = par("fg"), pars = NULL, frame.plot = axes,
horizontal = FALSE, ann = TRUE,
add = FALSE, at = NULL, show.names = NULL,
…)a list containing data summaries to be used in constructing
the plots. These are usually the result of a call to
boxplot, but can be generated in any fashion.
if notch is TRUE, a notch is drawn in each
side of the boxes. If the notches of two plots do not overlap then
the medians are significantly different at the 5 percent level.
a vector giving the relative widths of the boxes making up the plot.
if varwidth is TRUE, the boxes are drawn
with widths proportional to the square-roots of the number of
observations in the groups.
if outline is not true, the outliers are not
drawn.
numeric in (0,1). When notch = TRUE, the
fraction of the box width that the notches should use.
character or numeric (vector), the color of the box
borders. Is recycled for multiple boxes. Is used as default for
the boxcol, medcol, whiskcol, staplecol,
and outcol options (see below).
character, indicating if any axis should be drawn in
logarithmic scale, as in plot.default.
logical, indicating if a ‘frame’
(box) should be drawn; defaults to TRUE, unless
axes = FALSE is specified.
logical indicating if the boxplots should be
horizontal; default FALSE means vertical boxes.
a logical value indicating whether the default annotation (title and x and y axis labels) should appear on the plot.
logical, if true add boxplot to current plot.
numeric vector giving the locations where the boxplots
should be drawn, particularly when add = TRUE; defaults to
1:n where n is the number of boxes.
Set to TRUE or FALSE to override the
defaults on whether an x-axis label is printed for each group.
graphical parameters (etc) can be passed as
arguments to this function, either as a list (pars) or
normally(…), see the following. (Those in …
take precedence over those in pars.)
Currently, yaxs and ylim are used ‘along the
boxplot’, i.e., vertically, when horizontal is
false, and xlim horizontally.
xaxt, yaxt, las, cex.axis, and
col.axis are passed to axis, and main,
cex.main, col.main, sub, cex.sub,
col.sub, xlab, ylab, cex.lab, and
col.lab are passed to title.
In addition, axes is accepted (see
plot.window), with default TRUE.
The following arguments (or pars components) allow further
customization of the boxplot graphics. Their defaults are typically
determined from the non-prefixed version (e.g., boxlty from
lty), either from the specified argument or pars
component or the corresponding par one.
a scale factor to be applied to all boxes. When there
are only a few groups, the appearance of the plot can be improved by
making the boxes narrower. The default depends on at and
typically is
staple and outlier line width expansion, proportional to box width; both default to 0.5.
box outline type, width,
color, and fill color (which currently defaults to col and will
in future default to par("bg")).
median line type,
line width, point character, point size expansion, color, and
background color. The default medpch = NA suppresses the
point, and medlty = "blank" does so for the line.
Note thatmedlwd defaults to
lwd.
whisker line type (default:
"dashed"), width, and color.
staple (= end of whisker) line type, width, and color.
outlier line
type, line width, point character, point size expansion, color, and
background color. The default outlty = "blank" suppresses the
lines and outpch = NA suppresses points.
An invisible vector, actually identical to the at argument,
with the coordinates ("x" if horizontal is false, "y" otherwise) of
box centers, useful for adding to the plot.
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
# NOT RUN {
require(stats)
set.seed(753)
(bx.p <- boxplot(split(rt(100, 4), gl(5, 20))))
op <- par(mfrow = c(2, 2))
bxp(bx.p, xaxt = "n")
bxp(bx.p, notch = TRUE, axes = FALSE, pch = 4, boxfill = 1:5)
bxp(bx.p, notch = TRUE, boxfill = "lightblue", frame = FALSE,
outl = FALSE, main = "bxp(*, frame= FALSE, outl= FALSE)")
bxp(bx.p, notch = TRUE, boxfill = "lightblue", border = 2:6,
ylim = c(-4,4), pch = 22, bg = "green", log = "x",
main = "... log = 'x', ylim = *")
par(op)
op <- par(mfrow = c(1, 2))
## single group -- no label
boxplot (weight ~ group, data = PlantGrowth, subset = group == "ctrl")
## with label
bx <- boxplot(weight ~ group, data = PlantGrowth,
subset = group == "ctrl", plot = FALSE)
bxp(bx, show.names=TRUE)
par(op)
# }
# NOT RUN {
<!-- %% examples for new (S+ like) features -->
# }
# NOT RUN {
z <- split(rnorm(1000), rpois(1000, 2.2))
boxplot(z, whisklty = 3, main = "boxplot(z, whisklty = 3)")
## Colour support similar to plot.default:
op <- par(mfrow = 1:2, bg = "light gray", fg = "midnight blue")
boxplot(z, col.axis = "skyblue3", main = "boxplot(*, col.axis=..,main=..)")
plot(z[[1]], col.axis = "skyblue3", main = "plot(*, col.axis=..,main=..)")
mtext("par(bg=\"light gray\", fg=\"midnight blue\")",
outer = TRUE, line = -1.2)
par(op)
## Mimic S-Plus:
splus <- list(boxwex = 0.4, staplewex = 1, outwex = 1, boxfill = "grey40",
medlwd = 3, medcol = "white", whisklty = 3, outlty = 1, outpch = NA)
boxplot(z, pars = splus)
## Recycled and "sweeping" parameters
op <- par(mfrow = c(1,2))
boxplot(z, border = 1:5, lty = 3, medlty = 1, medlwd = 2.5)
boxplot(z, boxfill = 1:3, pch = 1:5, lwd = 1.5, medcol = "white")
par(op)
## too many possibilities
boxplot(z, boxfill = "light gray", outpch = 21:25, outlty = 2,
bg = "pink", lwd = 2,
medcol = "dark blue", medcex = 2, medpch = 20)
# }
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