lattice (version 0.17-25)

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(),
          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(),
            subscripts,
            subset)
## S3 method for class 'numeric':
densityplot(x, data = NULL, xlab, \dots)
do.breaks(endpoints, nint)

Arguments

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 condi

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"

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 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 specifies t

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 i

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 space

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 way

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

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, 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 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, 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.

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

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)