sieveplot {vcd}R Documentation

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

## Default S3 method:
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).

Author(s)

David Meyer
david.meyer@ci.tuwien.ac.at

References

H. Riedwyl & M. Schüpbach (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)
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