vcd (version 0.1-3.5)

sieveplot: Sieve Plots

Description

Visualization of two-way contingency tables: plots rectangles with surfaces proportional to the expected cell frequencies and filled with a number of squares equal to the expected frequencies. Thus, the densities visualize the deviations of the observed from the expected values.

Usage

## S3 method for class 'default':
sieveplot(x, reverse.y = TRUE,
          type = c("sieve", "expected"), main = NULL,
          values = c("none", "cells", "margins", "both"),
          frequencies = c("absolute", "relative"),
          sieve.colors = c("red","blue"),
          sieve.lty = c("longdash", "solid"),
          exp.color = "gray", exp.lty = "dotted",
          margin = 0.01, cex.main = 2, cex.lab = 1.5,
          xlab = names(dimnames(x))[2],
          ylab = names(dimnames(x))[1], ...)
## S3 method for class 'formula':
sieveplot(formula, data = NULL, ..., subset)

Arguments

x

a two-way contingency table, as generated by table.

reverse.y

if TRUE, the y axis is reversed (i.e., the rectangles' positions correspond to the contingency table).

type

expected fills the rectangles according to the expected frequencies.

main

user specified title.

values

optionally, the frequencies of the cells or margins or of both can be plotted.

frequencies

chooses the type of these frequencies: relative or absolute.

sieve.colors, sieve.lty

vectors with up to two color/line type entries: the first is used for negative and the second for positive deviations from the expected frequencies.

exp.color, exp.lty

color/line type entry for the expected values grid.

margin

lines of margin between the cell rectangles.

cex.main

font size of title.

cex.lab

font size of labels.

xlab, ylab

labels of x- and y-axis.

formula

a formula, such as y ~ x. For details, see xtabs.

data

a data.frame (or list), or a contingency table from which the variables in `formula' should be taken.

subset

an optional vector specifying a subset of observations to be used for plotting.

...

further graphics parameters (see par).

References

H. Riedwyl & M. Sch�pbach (1994), Parquet diagram to plot contingency tables. In F. Faulbaum (ed.), Softstat '93: Advances in Statistical Software, 293-299. Gustav Fischer, New York.

M. Friendly (2000), Visualizing Categorical Data, SAS Institute, Cary, NC.

See Also

mosaicplot

Examples

data(HairEyeColor)

## aggregate over `sex':
(tab <- margin.table(HairEyeColor, c(2,1)))

## plot expected values:
sieveplot(tab, type = "expected", values = "both")

## plot sieve diagram:
sieveplot(tab)

## an example for the formula interface:
data(VisualAcuity)
sieveplot(Freq ~ right + left,  data = VisualAcuity, reverse.y = FALSE)