| itemFrequencyPlot {arules} | R Documentation |
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).
itemFrequencyPlot(x, ...)
## S4 method for signature 'itemMatrix':
itemFrequencyPlot(x, type = "relative",
support = NULL, topN = NULL,
population = NULL, popCol = "black", popLwd = 1,
lift = FALSE, horiz = FALSE,
names = TRUE, cex.names = par("cex.axis"),
xlab = NULL, ylab = NULL, mai = NULL, ...)
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. |
support |
"numeric"; only display items which have a support of
at least support. If no population is given, support is calculated
from x otherwise from the population. Support is interpreted relative
or absolute according to the setting of type. |
topN |
"numeric"; only plot the topN
items with the highest item frequency or lift (if lift = TRUE).
The items are plotted ordered by descending support. |
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. |
popCol |
plotting color for population. |
popLwd |
line width for population. |
lift |
"logical"; plot the lift ratio between instead
of frequencies. The lift ratio is gives how many times an item is
more frequent in x than in population. |
horiz |
"logical"; If FALSE (default),
the bars are drawn vertically. If TRUE, the bars are
drawn horizontally. |
names |
"logical"; should the names (bar labels) displayed? |
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'). |
A numeric vector with the midpoints of the drawn bars; useful for adding to the graph.
itemFrequency,
itemMatrix-class
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
# (for first 72 variables/items)
itemFrequencyPlot(Adult.largeIncome[, 1:72],
population = Adult[, 1:72])
# plot lift ratio (frequency in x / frequency in population)
# for items with a support of 20% in the population
itemFrequencyPlot(Adult.largeIncome,
population = Adult, support = 0.2,
lift = TRUE, horiz = TRUE)