Tables can also be used to support graphics in R. A traditional bar plot, showing the total count for each variable, is most easily made by plotting a one dimensional table.
Using the baseball player data from before:
barplot(table(tab$position))
If you make a plot of a table that has two or more dimensions you get a mosaic plot, which is very difficult to read.
Tables can also be made multidimensional with the ftable() function, short for “flat table”. Like addmargins() and prop.table() this function only works when applied to an existing table. Here is a three dimensional flat table using the carstuff data.
t <- with(carstuff,(table(safety,class,buying)))
ftable(t)
buying vhigh high med low
safety class
high unacc 98 75 52 52
acc 46 69 56 33
good 0 0 10 20
vgood 0 0 26 39
med unacc 118 105 72 62
acc 26 39 59 56
good 0 0 13 26
vgood 0 0 0 0
low unacc 144 144 144 144
acc 0 0 0 0
good 0 0 0 0
vgood 0 0 0 0
Without using ftable() you still get a similar output from the table, but in a form that’s extremely difficult to read.
Intuitor 