B_03_histogram: Histograms and Kernel Density Plots

Description

Draw Histograms and Kernel Density Plots, possibly conditioned on other variables.

Usage

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(as.numeric(x),
                          finite = TRUE), prop = 0.04),
          breaks,
          equal.widths = TRUE,
          drop.unused.levels =
              lattice.getOption("drop.unused.levels"),
          ...,
          lattice.options = NULL,
          default.scales = list(),
          default.prepanel =
              lattice.getOption("prepanel.default.histogram"),
          subscripts,
          subset)
## S3 method for class 'numeric':
histogram(x, data = NULL, xlab, \dots)
## S3 method for class 'factor':
histogram(x, data = NULL, xlab, \dots)
## 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, weights,
            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(),
            default.prepanel =
                lattice.getOption("prepanel.default.densityplot"),
            subscripts,
            subset)
## S3 method for class 'numeric':
densityplot(x, data = NULL, xlab, \dots)
do.breaks(endpoints, nint)

Arguments

The object on which method dispatch is carried out. For the formula method, x can be a formula of the form ~ x | g1 * g2 * ..., indicating that histograms or kernel density estimates of the x

data

For the formula method, an optional data source (usually a
    data frame) in which variables are to be evaluated (see
    xyplot for details).  data should not be
    specified for

type

A character string indicating the type of histogram that is to be
    drawn.  "percent" and "count" give relative frequency
    and frequency histograms respectively, and can be misleading when
    breakpoints are not equally spa

nint

An integer specifying the number of histogram bins, applicable only
    when breaks is unspecified or NULL in the call.
    Ignored when the variable being plotted is a factor.

endpoints

A numeric vector of length 2 indicating the range of x-values 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 s

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

equal.widths

A logical flag, relevant only when breaks=NULL.  If
    TRUE, equally spaced bins will be selected, otherwise,
    approximately equal area bins will be selected (typically producing
    unequally spaced breakpoints).

n

Integer, giving the number of points at which the kernel density is
    to be evaluated.  Passed on as an argument to density.

panel

A function, called once for each panel, that uses the packet (subset
    of panel variables) corresponding to the panel to create a display.
    The default panel functions panel.histogram and
    <

allow.multiple, outer

See xyplot.

auto.key

See xyplot.

aspect

See xyplot.

prepanel

See xyplot.

scales

See xyplot.

strip

See xyplot.

groups

See xyplot.  Note that the default panel function for
    histogram does not support grouped displays, whereas the one
    for densityplot does.

xlab, ylab

See xyplot.

xlim, ylim

See xyplot.

drop.unused.levels

See xyplot.

lattice.options

See xyplot.

default.scales

See xyplot.

subscripts

See xyplot.

subset

See xyplot.

default.prepanel

Fallback prepanel function. See xyplot.

weights

numeric vector of weights for the density
    calculations, evaluated in the non-standard manner used for
    groups and terms in the formula, if any.  If this is
    specified, it is subsetted using subscripts inside the panel

bw, adjust, width

Arguments controlling bandwidth.  Passed on as arguments to
    density.

kernel, window

The choice of kernel.  Passed on as arguments to
    density.

give.Rkern

Logical flag, passed on as argument to density.
    This argument is made available only for ease of implementation, and
    will produce an error if TRUE.

from, to, cut

Controls range over which density is evaluated.  Passed on as
    arguments to density.

na.rm

Logical flag specifying whether NA values should be ignored.
    Passed on as argument to density, but unlike in
    density, the default is TRUE.

...

Further arguments.  See corresponding entry in
    xyplot for non-trivial details.

`Value`

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.

`Details`

histogram draws Conditional Histograms, and densityplot
  draws Conditional Kernel Density Plots.  The default panel function
  uses the density function to compute the density
  estimate, and all arguments accepted by density can be
  specified in the call to densityplot to control the output.
  See documentation of density for details.  Note that 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.

`References`

Sarkar, Deepayan (2008) Lattice: Multivariate Data
    Visualization with R, Springer.
  http://lmdvr.r-forge.r-project.org/

`See Also`

xyplot,
  panel.histogram,
  density,
  panel.densityplot,
  panel.mathdensity,
  Lattice

`Examples`

Run this coderequire(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)
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