Commit 4ec7cb75 authored by agebhard's avatar agebhard

add last changes from Martin Maechler

ready for release as 0.5-1
parent 840a8ad1
......@@ -3,5 +3,5 @@ akima Waveform Distortion Data for Bivariate
aspline Univariate Akima interpolation
interp Gridded Bivariate Interpolation for Irregular
Data
interpp Pointwise Bivariate Interpolation for Irregular
Data
interpp Pointwise Bivariate Interpolation for
Irregular Data
......@@ -7,18 +7,14 @@ interp.new <-
if(!(all(is.finite(x)) && all(is.finite(y)) && all(is.finite(z))))
stop("missing values and Infs not allowed")
if(!is.null(ncp)) {
if(ncp != 0) {
cat("ncp not supported, it is automatically choosen by Fortran code\n")
}
else {
cat("linear interpolation not yet implemented with interp.new().\n")
stop("use interp.old().")
}
}
if(linear) {
cat("linear interpolation not yet implemented with interp.new().\n")
stop("use interp.old().")
if(ncp != 0)
warning("'ncp' not supported, it is automatically choosen by Fortran code\n")
else
linear <- TRUE
}
if(linear)
stop("linear interpolation not implemented in interp.new().\n",
"use 'interp()' (or 'interp.old()').")
drx <- diff(range(x))
dry <- diff(range(y))
......
......@@ -56,7 +56,7 @@ interp.new(x, y, z, xo = seq(min(x), max(x), length = 40),
\item{linear}{logical -- indicating wether linear or spline
interpolation should be used. supersedes old \code{ncp} parameter}
\item{ncp}{
deprecated, use parameter \code{linear}. Now only used by
deprecated, use parameter \code{linear}. Now only used by
\code{interp.old()}.
meaning was:
......@@ -101,14 +101,15 @@ interp.new(x, y, z, xo = seq(min(x), max(x), length = 40),
interpolation the old version is choosen, but spline interpolation is
done by the new version.
Earlier versions (pre 0.5-1) of \code{interp} used the parameter
Earlier versions (pre 0.5-1) of \code{interp} used the parameter
\code{ncp} to choose between linear and cubic interpolation, this is now done
by setting the logical parameter \code{linear}. Use of \code{ncp} is still
by setting the logical parameter \code{linear}. Use of \code{ncp} is still
possible, but is deprecated.
The resulting structure is suitable for input to the
functions \code{contour} and \code{image}. Check the requirements of
these functions when choosing values for \code{xo} and \code{yo}.
functions \code{\link{contour}} and \code{\link{image}}. Check
the requirements of these functions when choosing values for
\code{xo} and \code{yo}.
}
\details{
If \code{linear} is \code{TRUE} (default), linear
......@@ -125,26 +126,23 @@ interp.new(x, y, z, xo = seq(min(x), max(x), length = 40),
user defined function).
The triangulation scheme used by \code{interp} works well if \code{x}
and \code{y} have
similar scales but will appear stretched if they have very different
scales. The spreads of \code{x} and \code{y} must be within four
orders of magnitude of each other for \code{interp} to work.
and \code{y} have similar scales but will appear stretched if they have
very different scales. The spreads of \code{x} and \code{y} must be
within four orders of magnitude of each other for \code{interp} to work.
}
\references{
Akima, H. (1978). A Method of Bivariate Interpolation and
Smooth Surface Fitting for Irregularly Distributed Data Points.
ACM Transactions on Mathematical Software,
\bold{4}, 148-164.
ACM Transactions on Mathematical Software \bold{4}, 148-164.
Akima, H. (1996). Algorithm 761: scattered-data surface fitting that has
the accuracy of a cubic polynomial.
ACM Transactions on Mathematical Software,
\bold{22}, 362--371
ACM Transactions on Mathematical Software \bold{22}, 362--371.
}
\seealso{
\code{\link{contour}}, \code{\link{image}},
\code{\link{approx}}, \code{\link{spline}},
\code{\link{aspline}},
\code{\link{outer}}, \code{\link{expand.grid}}.
}
\examples{
......@@ -162,8 +160,8 @@ points (akima, pch = 3)
akima.smooth <-
with(akima, interp(x, y, z, xo=seq(0,25, length=100),
yo=seq(0,20, length=100)))
image (akima.smooth)
contour(akima.smooth, add=TRUE)
image (akima.smooth, main = "interp(<akima data>, *) on finer grid")
contour(akima.smooth, add = TRUE, col = "thistle")
points(akima, pch = 3, cex = 2, col = "blue")
# use triangulation package to show underlying triangulation:
if(library(tripack, logical.return=TRUE))
......@@ -171,9 +169,9 @@ if(library(tripack, logical.return=TRUE))
# use only 15 points (interpolation only within convex hull!)
akima.part <- with(akima, interp(x[1:15], y[1:15], z[1:15]))
image (akima.part)
image (akima.part, "interp() on subset of only 15 points")
contour(akima.part, add=TRUE)
points(akima$x[1:15],akima$y[1:15])
points(akima$x[1:15],akima$y[1:15], col = "blue")
## spline interpolation, two variants (AMS 526 "Old", AMS 761 "New")
## -----------------------------------------------------------------
......@@ -184,7 +182,7 @@ table(is.na(akima.sO$z)) ## 3990 NA's; = 40 \%
akima.sO <- with(akima,
interp.old(x,y,z, xo=seq(0,25, length=100), yo=seq(0,20, len=100), ncp = 4))
sum(is.na(akima.sO$z)) ## still 3429
image (akima.sO) # almost useless
image (akima.sO, main = "interp.old(*, ncp = 4) [almost useless]")
contour(akima.sO, add = TRUE)
## "New:"
......@@ -195,7 +193,8 @@ akima.spl <- with(akima, interp(x,y,z, xo=seq(0,25, length=100),
yo=seq(0,20, length=100),
linear=FALSE))
contour(akima.spl) ; points(akima)
contour(akima.spl, main = "smooth interp(*, linear = FALSE)")
points(akima)
full.pal <- function(n) hcl(h = seq(340, 20, length = n))
cool.pal <- function(n) hcl(h = seq(120, 0, length = n) + 150)
......@@ -203,6 +202,7 @@ warm.pal <- function(n) hcl(h = seq(120, 0, length = n) - 30)
filled.contour(akima.spl, color.palette = full.pal,
plot.axes = { axis(1); axis(2);
title("smooth interp(*, linear = FALSE");
points(akima, pch = 3, col= hcl(c=100, l = 20))})
# no extrapolation!
......
......@@ -120,7 +120,10 @@ dupfun = NULL, ncp)
\bold{22}, 362-371.
}
\seealso{
\code{\link[base]{contour}}, \code{\link[base]{image}}, \code{\link[base]{approx}}, \code{\link[base]{spline}}, \code{\link[base]{outer}}, \code{\link[base]{expand.grid}},\code{\link{interp}}.
\code{\link[base]{contour}}, \code{\link[base]{image}},
\code{\link[base]{approx}}, \code{\link[base]{spline}},
\code{\link[base]{outer}}, \code{\link[base]{expand.grid}},
\code{\link{interp}}, \code{\link{aspline}}.
}
\examples{
data(akima)
......
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