See help pages for detailed descriptions of the functions used in this section.
`barplot()`: construct bar plots for categorical variables.
`pie()`: construct pie charts for categorical variables.
`title()`: add titles to an existing plot.
`par()`: set graphical parameters.
`scale()`: center and scale each column of a numeric matrix.
`margin.table()`: obtain margin totals for an array of frequency counts.
`mosaicplot()`: mosaic plot for 2-d frequency table.
`assocplot()`: plot deviations from independence for 2-d frequency table.
`hist()`: histogram for continuous variables.
`pairs()`: plot on one page all pairwise scatter plots of multivariate data matrix.
`mtext()`: add text to margins of an existing plot.
`plot()`: generic function for plotting. The type of plot produced depends on the type
of data specified by its arguments.
`names()`: returns or sets the names of a vector or data frame. The names of a data
frame correspond to the column names of the matrix.

2018-02-14