You can draw pie charts using the same structure as bar graphs.
The camembert command draws pie charts.
camembert takes one argument: M, a matrix, where each row consists of a label followed by one or
more values. If the labels are followed by more than one value,
then the first row needs to be identifiers.
camembert(M) draws a pie chart with a sector for each
label, whose size is determined by the corresponding value. If the
matrix has more than two columns, then there will be a pie chart for
each column of values.