Plot pairs of variables against each other.
data is the data holding the variables to plot. It may be either a
table or a struct. Each variable or field in the
or struct is considered to be one variable. Each must hold a vector, and
all the vectors of all the variables must be the same size.
plot_type is a charvec indicating what plot type to do in each subplot.
"scatter" is the default.) Valid plot_type values are:
A plain scatter plot.
A scatter plot + fitted line, like R’s
fig is an optional figure handle to plot into. If omitted, a new figure is created.
Returns the created figure, if the output is captured.