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#
# fields is a package for analysis of spatial data written for
# the R software environment.
# Copyright (C) 2024 Colorado School of Mines
# 1500 Illinois St., Golden, CO 80401
# Contact: Douglas Nychka, douglasnychka@gmail.com,
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
# This program 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with the R software environment if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
# or see http://www.r-project.org/Licenses/GPL-2
##END HEADER
addMarginsGridList<- function( xObs, gridList, NNSize){
np<- NNSize
# ranges and sizes for the inoput grid and the obs
xMin<- min(xObs[,1])
xMax<- max(xObs[,1])
yMin<- min(xObs[,2])
yMax<- max(xObs[,2])
gridXMin<- gridList$x[1]
gridYMin<- gridList$y[1]
dx<- gridList$x[2] - gridList$x[1]
nx<- length( gridList$x)
dy<- gridList$y[2] - gridList$y[1]
ny<- length( gridList$y)
#### x grid block
ind1<- floor( (xMin - gridXMin)/dx)
ind2<- ceiling( (xMax - gridXMin)/dx)
if( (ind1 < 0)| (ind2 > nx) ) {
stop("locations outside of x grid" )
}
indRangeX<- c( min( ind1 - np , 0), max( ind2 + np +1 ,nx ))
xGrid<- (indRangeX[1]:(indRangeX[2] - 1)) *dx + gridXMin
ind1<- floor( (yMin - gridYMin)/dy)
ind2<- ceiling( (yMax - gridYMin)/dy)
if( (ind1 < 0)| (ind2 > ny) ) {
stop("locations outside of y grid" )
}
#### y grid block
indRangeY<- c( min( ind1 - np , 0), max( ind2 + np +1 , ny))
yGrid<- (indRangeY[1]:(indRangeY[2] - 1)) *dy + gridYMin
# new gridList contains the orginal grid
# up to round off based on integer steps in dx and dy and extends
# it so that
# there are np grid points beyond the min and max ranges for
# the original ranges.
gridListNew<- list( x = xGrid,
y = yGrid)
# these indices are used to locate the original grid as a subset of the larger
# one
# the strange coding is due to the fact that the original grid and the larger one
# may differ at the level of roundoff error.
indX<- c(
which.min( abs(gridList$x[1] - gridListNew$x)),
which.min( abs(gridList$x[nx] - gridListNew$x))
)
indY<- c(
which.min( abs(gridList$y[1] - gridListNew$y)),
which.min( abs(gridList$y[ny] - gridListNew$y))
)
return(
list(gridListNew = gridListNew, gridList = gridList,
indX= indX,
indY= indY,
np=np )
)
}
#
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