xyz-contour plot (irregular grid)

I'm not sure if there is a single function, but a quick script
would look something like this and would be easily adjusted

attach(mtcars)
mtcars.ls <- loess(mpg~wt*hp)
wtg <- seq(min(wt), max(wt), length.out=50)
hpg <- seq(min(hp), max(hp), length.out=50)
grid <- expand.grid(wt=wtg, hp=hpg)
mpg.fit <- predict(mtcars.ls, grid)
contour(wtg, hpg, mpg.fit, xlab="Weight (1,000 lbs)", 
  ylab="Horsepower")
points(wt, hp, pch=20)

-------------------------------------
David L Carlson
Department of Anthropology
Texas A&M University
College Station, TX 77840-4352

-----Original Message-----
From: r-help-bounces at r-project.org
[mailto:r-help-bounces at r-project.org] On Behalf Of ivo welch
Sent: Thursday, November 21, 2013 10:35 PM
To: r-help
Subject: [R] xyz-contour plot (irregular grid)

Dear R users:  before I try to undertake my own rewrite, has
anyone already
written a contour function that does not require a regularly
spaced grid,
preferably plot.contour(x,y,z,...)?

(it would be nice if it were based on loess() and plot()?
further
annotations, changes, etc., would then be easier.)

sincerely, /iaw

----
Ivo Welch (ivo.welch at gmail.com)


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code.

Dear R users:  before I try to undertake my own rewrite, has anyone already
written a contour function that does not require a regularly spaced grid,
preferably plot.contour(x,y,z,...)?

(it would be nice if it were based on loess() and plot()?  further
annotations, changes, etc., would then be easier.)

The akima function in the package by the same name provides that facility.

David Winsemius
Alameda, CA, USA