R help - Nov 2013 - 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@gmail.com)

	[[alternative HTML version deleted]]

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)

	[[alternative HTML version deleted]]

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On Nov 21, 2013, at 8:35 PM, ivo welch wrote:
> 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