barchartGC function

Easy Bar Charts

Wrapper for barchart in package lattice. Creates a bar chart from raw data using formula-data syntax similar to that of xtabs, or from a table. Defaults to a "standard" bar chart in which the bars are vertical and un-stacked. Supports percentage bar charts.

barchartGC(x,data=parent.frame(),type="frequency",flat=FALSE,auto.key=TRUE,
                       horizontal=FALSE,stack=FALSE,...)

Arguments

• x: Either a formula or an object that can be coerced to a table. If formula, it must be of the form ~var or ~var1+var2.
• data: Usually a data frame that supplies the variables in x. Variables not in the data argument are searched for in the parent environment.
• type: Possible values are "frequency" and "percent".
• flat: If set to TRUE, will produce bar chart that resembles the layout of xtabs
• auto.key: Provides a simple key
• horizontal: Determines orientation of the bars (overridden by flat)
• stack: Determines whether bars for tallies are stacked on each other or placed next to one another (overriden by flat)
• ...: other arguments passed to barchart: these include main, sub, and xlab, which are likely to be familiar to students from other lattice graphical functions. An error is possible if other arguments pertaining to legends are passed (hopefully anyone interested in such will have moved on to barchart).

Returns

A trellis object describing the bar chart.

Examples

#bar chart of counts for one factor variable:
barchartGC(~sex,data=m111survey)

#bar chart with percentages and title:
barchartGC(~sex,data=m111survey,
   type="percent",
   main="Distribution of Sex")

#bar chart of counts, to study the relationship between
#two factor variables:
barchartGC(~sex+seat,data=m111survey)

#percentage bar chart, two factor variables:
barchartGC(~sex+seat,data=m111survey,type="percent")

#From tabulated data:
sexseat <- xtabs(~sex+seat,data=m111survey)
barchartGC(sexseat,type="percent",main="Sex and Seating Preference")

#from tabulated data:
dieTosses <- c(one=8,two=18,three=11,four=7,five=9,six=7)
barchartGC(dieTosses,main="60 Rolls of a Die")

# a "flat" bar chart, pictorial version of xtabs() 
barchartGC(~sex+seat,data=m111survey,flat=TRUE,ylab="Sex")

# a "flat" bar chart, pictorial version of xtabs() 
barchartGC(~sex+seat,data=m111survey,type="percent",flat=TRUE,ylab="Sex")

Author(s)

Homer White hwhite0@georgetowncollege.edu