freqpolygon: Frequency Polygons

In mosaic: Project MOSAIC Statistics and Mathematics Teaching Utilities

Frequency Polygons

Description

Frequency polygons are an alternative to histograms that make it simpler to overlay multiple distributions.

Usage

freqpolygon(
  x,
  ...,
  panel = "panel.freqpolygon",
  prepanel = "prepanel.default.freqpolygon"
)

prepanel.default.freqpolygon(
  x,
  darg = list(),
  plot.points = FALSE,
  ref = FALSE,
  groups = NULL,
  subscripts = TRUE,
  jitter.amount = 0.01 * diff(current.panel.limits()$ylim),
  center = NULL,
  nint = NULL,
  breaks = NULL,
  width = darg$width,
  type = "density",
  ...
)

panel.freqpolygon(
  x,
  darg = list(),
  plot.points = FALSE,
  ref = FALSE,
  groups = NULL,
  weights = NULL,
  jitter.amount = 0.01 * diff(current.panel.limits()$ylim),
  type = "density",
  breaks = NULL,
  nint = NULL,
  center = NULL,
  width = darg$width,
  gcol = trellis.par.get("reference.line")$col,
  glwd = trellis.par.get("reference.line")$lwd,
  h,
  v,
  ...,
  identifier = "freqpoly"
)

Arguments

x	a formula or a numeric vector
...	additional arguments passed on to histogram() and panel.
panel	a panel function
prepanel	a prepanel function
darg	a list of arguments for the function computing the frequency polygon. This exists primarily for compatibility with densityplot and is unlikely to be needed by the end user.
plot.points	one of TRUE, FALSE, "jitter", or "rug" indicating how points are to be displayed
ref	a logical indicating whether a horizontal reference line should be added (roughly equivalent to h=0)
groups, weights, jitter.amount, identifier	as in densityplot() or histogram()
subscripts	as in other lattice prepanel functions
center	center of one of the bins
nint	an approximate number of bins for the frequency polygon
breaks	a vector of breaks for the frequency polygon bins
width	width of the bins
type	one of 'density', 'percent', or 'count'
gcol	color of guidelines
glwd	width of guidelines
h, v	a vector of values for additional horizontal and vertical lines

Value

a trellis object

Note

This function make use of histogram to determine overall layout. Often this works reasonably well but sometimes it does not. In particular, when groups is used to overlay multiple frequency polygons, there is often too little head room. In the latter cases, it may be necessary to use ylim to determine an appropriate viewing rectangle for the plot.

Examples

freqpolygon(~age | substance, data=HELPrct, v=35)
freqpolygon(~age, data=HELPrct, labels=TRUE, type='count')
freqpolygon(~age | substance, data=HELPrct, groups=sex)
freqpolygon(~age | substance, data=HELPrct, groups=sex, ylim=c(0,0.11))
## comparison of histogram and frequency polygon
histogram(~eruptions, faithful, type='density', width=.5)
ladd( panel.freqpolygon(faithful$eruptions, width=.5 ))

mosaic documentation built on May 29, 2024, 5:27 a.m.