On Sep 13, 2010, at 1:54 AM, Uwe Dippel wrote:
Though I have read quite a bit, and tried quite a bit, I have yet to
find a nice way to overlay 2 or more curves in the same plot, with
different ranges.
The different axes could be a problem but if you construct both with
predefined coordinates systems and scale appropriately it should work
out. See the twoord.plot function in plotrix.
Here is simplified sample code to demonstrate the question:
> plot(2*(seq(1,5)), type="l", axes=FALSE)
? lines
lines(1.5*(seq(2,5)), type="b")
> curve(2*(seq(1,5)), type="b", add=TRUE)
Error in curve(2 * (seq(1, 5)), type = "b", add = TRUE) :
'expr' must be a function or an expression containing 'x'
> axis(2)
> curve(x^2, 1, 5, type="b", add=TRUE)
> axis(4)
Firstly, as an aside, I am not clear why 'curve' has a different
syntax compared to 'plot'. As a still beginner, I'd for one would be
happy to add curves to a plot; curves of just different parameters.
Though, I guess, there must be a good reason?
curve is like abline in that it draws from left x range to right x
range.
Mostly, however, I wonder how to plot a number of curves into an
original plot, that re-defines the min/max from the most recent curve.
lines() or segments()
In the example that I constructed, axis(2) does exactly the expected
thing.
What I want to do next, though, with the least effort, is to add
another function in a manner that the added function is scaled, not
according to the first function (plot), but to fit into the plotting
area. (The example above overshoots the range).
Plus, how can I subsequently add the axis suitable to the most
recent function? That is, how can I render axis(4) to displaying the
scale for the second graph, created with 'curve'?
There are many worked examples in the archives, as well as canned
solutions in widely used packages.
--
David Winsemius, MD
West Hartford, CT
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