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# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Library General Public
# License as published by the Free Software Foundation; either
# version 2 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Library General Public License for more details.
#
# You should have received A copy of the GNU Library General
# Public License along with this library; if not, write to the
# Free Foundation, Inc., 59 Temple Place, Suite 330, Boston,
# MA 02111-1307 USA
# Copyrights (C)
# for this R-port:
# 1999 - 2008, Diethelm Wuertz, Rmetrics Foundation, GPL
# Diethelm Wuertz <wuertz@itp.phys.ethz.ch>
# www.rmetrics.org
# for the code accessed (or partly included) from other R-ports:
# see R's copyright and license files
# for the code accessed (or partly included) from contributed R-ports
# and other sources
# see Rmetrics's copyright file
################################################################################
# FUNCTION: BIVARIATE GRIDDED INTERPOLATION:
# linearInterp Interpolates linearly irregularly spaced data points
# linearInterpp Interpolates linearly pointwise
################################################################################
linearInterp <-
function(x, y = NULL, z = NULL, gridPoints = 21,
xo = seq(min(x), max(x), length = gridPoints),
yo = seq(min(y), max(y), length = gridPoints))
{
# A function implemented by Diethelm Wuertz
# Description:
# Interpolates Linearly Irregularly Distributed Data Points
# Arguments:
# x, y, z - either three numeric vectors of equal length or if
# y and z are NULL, a list with entries x, y, a, or named
# data.frame with x in the first, y in the second, and z in
# the third column.
# gridPoints - number of grid points in x and y direction.
# xo, yo, a sequence of data points spanning the grid
# Note:
# Extrapolation is not possible in the case of linear interpolation.
# Value:
# A list with three elements, $x and $y which are vectors of length
# 'gridPoints' and $z which is a matrix of size 'gridPoints^2'.
# Requirements:
# akima Builtin Fortran Code.
# Example:
# set.seed(1953)
# x = runif(999)-0.5; y = runif(999)-0.5; z = cos(2*pi*(x^2+y^2))
# ans = linearInterp(x, y, z)
# persp(ans, theta = -50, phi = 30, col = "steelblue")
# Note:
# Uses Fortran akima Builtin
# FUNCTION:
if (!require(akima, quietly = TRUE))
stop("\n -- Package akima not available -- \n\n")
# Arguments:
if (is.list(x)) x = matrix(unlist(x), ncol = 3)
if (is.data.frame(x)) x = as.matrix.data.frame(x)
if (is.matrix(x)) {
z = x[, 3]
y = x[, 2]
x = x[, 1]
}
# Interpolation:
ans = .interp.old(x, y, z, xo, yo, ncp = 0, extrap = FALSE,
duplicate = "median", dupfun = NULL)
colnames(ans$z) = as.character(signif(ans$x, round(log(gridPoints), 0)))
rownames(ans$z) = as.character(signif(ans$y, round(log(gridPoints), 0)))
class(ans) = "gridData"
# Return Value:
ans
}
# ------------------------------------------------------------------------------
linearInterpp <-
function(x, y = NULL, z = NULL, xo, yo)
{
# A function implemented by Diethelm Wuertz
# Description:
# Interpolates Linearly Irregularly Distributed Data Points
# Arguments:
# x, y, z - either three numeric vectors of equal length or if
# y and z are NULL, a list with entries x, y, a, or named
# data.frame with x in the first, y in the second, and z in
# the third column.
# gridPoints - number of grid points in x and y direction.
# xo, yo, a sequence of data points for pointwise interpolation
# Note:
# Extrapolation is not possible in the case of linear interpolation.
# Value:
# A list with three elements, $x and $y which are vectors of length
# 'gridPoints' and $z which is a matrix of size 'gridPoints^2'.
# Requirements:
# akima Builtin Fortran Code.
# Example:
# set.seed(1953)
# x = runif(999)-0.5; y = runif(999)-0.5; z = cos(2*pi*(x^2+y^2))
# ans = linearInterpp(x, y, z, c(mean(x), 0, 100), c(mean(y), 0, 100))
# persp(ans, theta = -50, phi = 30, col = "steelblue")
# Note:
# Uses Fortran akima Builtin
# FUNCTION:
if (!require(akima, quietly = TRUE))
stop("\n -- Package akima not available -- \n\n")
# Arguments:
if (is.list(x)) x = matrix(unlist(x), ncol = 3)
if (is.data.frame(x)) x = as.matrix.data.frame(x)
if (is.matrix(x)) {
z = x[, 3]
y = x[, 2]
x = x[, 1]
}
# Interpolation:
ans = .interpp.old(x, y, z, xo, yo, ncp = 0, extrap = FALSE,
duplicate = "median", dupfun = NULL)
ans = data.frame(x = ans$x, y = ans$y, z = ans$z)
# Return Value:
ans
}
################################################################################
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