arules (version 0.2-6)

itemFrequencyPlot: Creating a Item Frequencies/Support Bar Plot

Description

Provides the generic function itemFrequencyPlot and the S4 method to create an item frequency bar plot for inspecting the item frequency distribution for objects based on itemMatrix (e.g., transactions, or items in itemsets and rules).

Usage

itemFrequencyPlot(x, ...)
## S3 method for class 'itemMatrix':
itemFrequencyPlot(x, type = "relative", 
    population = NULL, deviation = FALSE, horiz = FALSE, 
    cex.names =  par("cex.axis"), xlab = NULL, ylab = NULL, 
    mai = NULL, ...)

Arguments

x

the object to be plotted.

...

further arguments are passed on (see barplot from possible arguments).

type

a character string indicating whether item frequencies should be displayed relative of absolute.

population

object of same class as x; if x is a segment of a population, the population mean frequency for each item can be shown as a line in the plot.

deviation

"logical"; plot the relative deviation from the population mean instead of frequencies.

horiz

"logical"; If FALSE (default), the bars are drawn vertically. If TRUE, the bars are drawn horizontally.

cex.names

"numeric"; expansion factor for axis names (bar labels).

xlab

a character string with the label for the x axis (use an empty string to force no label).

ylab

a character string with the label for the y axis (see xlab).

mai

a numerical vector giving the plots margin sizes in inches (see `? par').

Value

• A numeric vector with the midpoints of the drawn bars; useful for adding to the graph.

See Also

itemMatrix-class

Examples

data(Adult)

# the following example compares the item frequencies
# of people with a large income (boxes) with the average in the data set
Adult.largeIncome <- Adult[Adult %in% 
	"income=large"]

# simple plot
itemFrequencyPlot(Adult.largeIncome)

# plot with the averages of the population plotted as a line 
# (first 72 variables/items)
itemFrequencyPlot(Adult.largeIncome[, 1:72], 
	population = Adult[, 1:72])

# plot of deviations from population mean (horizontal bars)
itemFrequencyPlot(Adult.largeIncome[, 1:72], 
        population = Adult[, 1:72], 
	deviation = TRUE, horiz = TRUE)