Plots including multiple regression lines are added to a matrix of plots generated with the GGally package in R.1
Built upon ggplot2, GGally provides templates
for combining plots into a matrix through the
Such a matrix of plots can be useful for quickly exploring the
relationships between multiple columns of data in a data frame.
upper arguments to the
ggpairs function specifies
the type of plot or data in each position of the lower or upper diagonal
of the matrix, respectively.
For continuous X and Y data, one can specify the
smooth option to
include a regression line.
To include more than one regression line in a plot (or to customize the
plot in any way beyond one of the predefined types), one simply
defines a function that returns the desired plot.
The function can then be included in the list provided to
The following code demonstrates inclusion of two regression lines
in each plot in the lower diagonal elements in which both X and Y
data are continuous.
The plot generated by the above code is included here.
Note that the default transparency of the
confidence interval works fairly well for being able to compare
the two types of regression curves.