lattice (version 0.11-8)

histogram: Histograms and Kernel Density Plots

Description

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

Usage

histogram(formula,
          data, 
          type = c("percent", "count", "density"),
          nint = if(is.factor(x)) length(levels(x))
                 else round(log2(length(x))+1),
          endpoints = range(x[!na.x]),
          breaks = if(is.factor(x)) seq(0.5, length = length(levels(x))
          + 1) else do.breaks(endpoints, nint),
          equal.widths = FALSE, 
          ...)
densityplot(formula, data, n = 50, plot.points = TRUE, ref = FALSE,
            ...)
do.breaks(endpoints, nint)

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.

synopsis

histogram(formula, data = parent.frame(), allow.multiple = is.null(groups) || outer, outer = FALSE, auto.key = FALSE, aspect = "fill", panel = "panel.histogram", prepanel = NULL, scales = list(), strip = TRUE, groups = NULL, xlab, xlim, ylab, ylim, type = c("percent", "count", "density"), nint = if (is.factor(x)) length(levels(x)) else round(log2(length(x)) + 1), endpoints = extend.limits(range(x[!is.na(x)]), prop = 0.04), breaks = if (is.factor(x)) seq(0.5, length = length(levels(x))+1) else do.breaks(endpoints, nint), equal.widths = TRUE, drop.unused.levels, ..., default.scales, subscripts = !is.null(groups), subset = TRUE) densityplot(formula, data = parent.frame(), allow.multiple = is.null(groups) || outer, outer = FALSE, auto.key = FALSE, aspect = "fill", panel = if (is.null(groups)) "panel.densityplot" else "panel.superpose", prepanel = NULL, scales = list(), strip = TRUE, groups = NULL, xlab, xlim, ylab, ylim, bw = NULL, adjust = NULL, kernel = NULL, window = NULL, width = NULL, give.Rkern = FALSE, n = 50, from = NULL, to = NULL, cut = NULL, na.rm = NULL, drop.unused.levels, ..., default.scales, panel.groups = "panel.densityplot", subscripts = !is.null(groups), subset = TRUE)

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.

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)