I've tried to figure out how to do this from what I read, but haven't
been successful. Suppose I have a dataframe with variables Date, X, and
Y (and maybe U, V, and Z) where X, Y, etc. have different units. I'd
like to plot Y vs. Time above X vs. Time, above one another.
For example, X is the number of gulls counted on a reservoir, and Y is
the number of coliform bacteria counted on a petri plate from a water
sample leaving the reservoir, so these have very different ranges. U and
V might be numbers of geese and numbers of ducks counted on the same days.
What commands would I use to create such a set of plots?
Thank you for any help.
David