vcd (version 0.9-9)

struc_assoc: Core-generating Function for Association Plots

Description

Core-generating function for strucplot returning a function producing association plots.

Usage

struc_assoc(compress = TRUE, xlim = NULL, ylim = NULL,
  yspace = unit(0.5, "lines"), xscale = 0.9, gp_axis = gpar(lty = 3))

Arguments

compress

logical; if FALSE, the space between the rows (columns) are chosen such that the total heights (widths) of the rows (column) are all equal. If TRUE, the space between the rows and columns is fixed and hence

xlim

either a $2 \times k$ matrix of doubles, $k$ the number of total columns of the plot, or a recycled vector from which such a matrix will be constructed. The columns of xlim correspond to the columns of the association plot, th

ylim

either a $2 \times k$ matrix of doubles, $k$ the number of total rows of the plot, or a recycled vector from which such a matrix will be constructed. The columns of ylim correspond to the rows of the association plot, the rows

xscale

scale factor resizing the tile's width, thus adding additional space between the tiles.

yspace

object of class "unit" specifying additional space separating the rows.

gp_axis

object of class "gpar" specifying the visual aspects of the tiles' baseline.

Value

• A function with arguments:
• residuals
  table of residuals.
• observed
  not used by struc_assoc.
• expected
  table of expected frequencies.
• spacing
  object of class "unit" specifying the space between the tiles.
• gp
  list of gpar objects used for the drawing the tiles.
• split_vertical
  vector of logicals indicating, for each dimension of the table, the split direction.

Details

This function is usually called by strucplot (typically when called by assoc) and returns a function used by strucplot to produce association plots.

References

Cohen, A. (1980), On the graphical display of the significant components in a two-way contingency table. Communications in Statistics---Theory and Methods, A9, 1025--1041.

Friendly, M. (1992), Graphical methods for categorical data. SAS User Group International Conference Proceedings, 17, 190--200. http://www.math.yorku.ca/SCS/sugi/sugi17-paper.html

See Also

assoc, strucplot, structable

Examples

## UCB Admissions
data("UCBAdmissions")
ucb <- aperm(UCBAdmissions)

## association plot for conditional independence
strucplot(ucb, expected = ~ Dept * (Admit + Gender),
  core = struc_assoc(ylim = c(-4, 4)), labeling_args = list(abbreviate = c(Admit = 3)))

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