histogram {lattice}  R Documentation 
Draw Histograms and Kernel Density Plots, possibly conditioned on other variables.
histogram(x, data, ...) densityplot(x, data, ...) ## S3 method for class 'formula': histogram(x, data, allow.multiple, outer = TRUE, auto.key = FALSE, aspect = "fill", panel = lattice.getOption("panel.histogram"), prepanel, scales, strip, groups, xlab, xlim, ylab, ylim, type = c("percent", "count", "density"), nint = if (is.factor(x)) nlevels(x) else round(log2(length(x)) + 1), endpoints = extend.limits(range(x, finite = TRUE), prop = 0.04), breaks, equal.widths = TRUE, drop.unused.levels = lattice.getOption("drop.unused.levels"), ..., lattice.options = NULL, default.scales = list(), subscripts, subset) ## S3 method for class 'numeric': histogram(x, data = NULL, xlab, ...) ## S3 method for class 'factor': histogram(x, data = NULL, xlab, ...) ## S3 method for class 'formula': densityplot(x, data, allow.multiple = is.null(groups)  outer, outer = !is.null(groups), auto.key = FALSE, aspect = "fill", panel = lattice.getOption("panel.densityplot"), prepanel, scales, strip, groups, xlab, xlim, ylab, ylim, bw, adjust, kernel, window, width, give.Rkern, n = 50, from, to, cut, na.rm, drop.unused.levels = lattice.getOption("drop.unused.levels"), ..., lattice.options = NULL, default.scales = list(), subscripts, subset) ## S3 method for class 'numeric': densityplot(x, data = NULL, xlab, ...) do.breaks(endpoints, nint)
x 
The object on which method dispatch is carried out.
For the formula method, a formula of the form ~ x  g1
* g2 * ... indicates that histograms or Kernel Density
estimates of x should be produced conditioned on the levels
of the (optional) variables g1, g2, ... . x can be
numeric (or factor for histogram ), and each of g1, g2,
... must be either factors or shingles.
As a special case, the right hand side of the formula can contain more than one variable separated by a + sign. What happens in
this case is described in details in the documentation for
xyplot . Note that in either form, all the variables
involved in the formula have to have same length.
For the numeric and factor methods, x
replaces the x vector described above. Conditioning is not
allowed in these cases.

data 
For the formula method, an optional data frame in which
variables are to be evaluated. Ignored with a warning in other
cases.

type 
Character string indicating type of histogram to be drawn.
"percent" and "count" give relative frequency
and frequency histograms, and can be misleading when breakpoints are
not equally spaced. "density" produces a density scale
histogram.
type defaults to "percent" , except when the
breakpoints are unequally spaced or breaks = NULL , when it
defaults to "density" .

nint 
Number of bins. Applies only when breaks is unspecified or
NULL in the call. Not applicable when the variable being
plotted is a factor.

endpoints 
vector of length 2 indicating the range of xvalues that is to be
covered by the histogram. This applies only when breaks is
unspecified and the variable being plotted is not a factor. In
do.breaks , this specifies the interval that is to be divided
up.

breaks 
usually a numeric vector of length (number of bins +
1) defining the breakpoints of the bins. Note that when breakpoints
are not equally spaced, the only value of type that makes
sense is density. When unspecified, the default is to use
breaks = seq_len(1 + nlevels(x))  0.5when x is a factor, and
breaks = do.breaks(endpoints, nint)otherwise. Breakpoints calculated in such a manner are used in all panels. Other values of breaks are possible, in which case they
affect the display in each panel differently. A special value of
breaks is NULL , in which case the number of bins is
determined by nint and then breakpoints are chosen according to
the value of equal.widths . Other valid values of
breaks are those of the breaks argument in
hist . This allows specification of breaks as
an integer giving the number of bins (similar to nint ), as a
character string denoting a method, and as a function.

equal.widths 
logical, relevant only when breaks=NULL .
If TRUE , equally spaced bins will be selected, otherwise,
approximately equal area bins will be selected (this would mean that
the breakpoints will not be equally spaced).

n 
number of points at which density is to be evaluated 
panel 
The function that uses the packet (subset of display variables) corresponding to a panel to create a display. Default panel functions are documented separately, and often have arguments that can be used to customize its display in various ways. Such arguments can usually be directly supplied to the high level function. 
allow.multiple, outer, auto.key, aspect, prepanel, scales,
strip, groups, xlab, xlim, ylab, ylim, drop.unused.levels,
lattice.options, default.scales, subscripts, subset 
See
xyplot 
bw, adjust, kernel, window, width, give.Rkern, from, to, cut,
na.rm 
arguments to density , passed on as appropriate

... 
Further arguments. See corresponding entry in
xyplot for nontrivial details. 
histogram
draws Conditional Histograms, while
densityplot
draws Conditional Kernel Density Plots. The
density estimate in densityplot
is actually calculated using
the function density
, and all arguments accepted by it can be
passed (as ...
) in the call to densityplot
to control
the output. See documentation of density
for details. (Note:
The default value of the argument n
of density
is
changed to 50.)
These and all other high level Trellis functions have several
arguments in common. These are extensively documented only in the
help page for xyplot
, which should be consulted to learn more
detailed usage.
do.breaks
is an utility function that calculates breakpoints
given an interval and the number of pieces to break it into.
An object of class "trellis"
. The
update
method can be used to
update components of the object and the
print
method (usually called by
default) will plot it on an appropriate plotting device.
The form of the arguments accepted by the default panel function
panel.histogram
is different from that in SPLUS. Whereas
SPLUS calculates the heights inside histogram
and passes only
the breakpoints and the heights to the panel function, here the
original variable x
is passed along with the breakpoints. This
allows plots as in the second example below.
Deepayan Sarkar Deepayan.Sarkar@Rproject.org
xyplot
,
panel.histogram
,
density
,
panel.densityplot
,
panel.mathdensity
,
Lattice
require(stats) histogram( ~ height  voice.part, data = singer, nint = 17, endpoints = c(59.5, 76.5), layout = c(2,4), aspect = 1, xlab = "Height (inches)") histogram( ~ height  voice.part, data = singer, xlab = "Height (inches)", type = "density", panel = function(x, ...) { panel.histogram(x, ...) panel.mathdensity(dmath = dnorm, col = "black", args = list(mean=mean(x),sd=sd(x))) } ) densityplot( ~ height  voice.part, data = singer, layout = c(2, 4), xlab = "Height (inches)", bw = 5)