[R-sig-Geo] GWmodel - create prediction raster at a finer spatial scale when using multiple independent variables

[Nikolaos Tziokas]

I am using the package GWmodel to predict at a finer spatial scale.
Basically, I want my output to be a single raster layer. For the GWR, I am
using one dependent and 2 independent variables. I don't know how to create
the prediction raster.

When using only one independent variable it's easy. For example:

library(GWmodel)
library(sp)
library(raster)

wd = "path/"
provoliko = "EPSG:7767"

# this is my fine res raster
tirs = raster(paste0(wd, "tirs.tif"))
regpoints <- as(tirs, "SpatialPoints")

# this df contains the coarse res variables
block.data = read.csv(paste0(wd, "block.data.csv"))

coordinates(block.data) <- c("x", "y")
proj4string(block.data) <- provoliko

eq1 <- ntl ~ tirs
abw = bw.gwr(eq1,
             data = block.data,
             approach = "AIC",
             kernel = "gaussian",
             adaptive = TRUE,
             p = 2,
             parallel.method = "omp",
             parallel.arg = "omp")

ab_gwr = gwr.basic(eq1,
                   data = block.data,
                   regression.points = regpoints,
                   bw = abw,
                   kernel = "gaussian",
                   adaptive = TRUE,
                   p = 2,
                   F123.test = FALSE,
                   cv = FALSE,
                   parallel.method = "omp",
                   parallel.arg = "omp")

ab_gwr

sp <- ab_gwr$SDF
sf <- st_as_sf(sp)

# intercept
intercept = as.data.frame(sf$Intercept)
intercept = SpatialPointsDataFrame(data = intercept, coords = regpoints)
gridded(intercept) <- TRUE
intercept <- raster(intercept)
raster::crs(intercept) <- provoliko

# slope
slope = as.data.frame(sf$tirs)
slope = SpatialPointsDataFrame(data = slope, coords = regpoints)
gridded(slope) <- TRUE
slope <- raster(slope)
raster::crs(slope) <- provoliko

gwr_pred = intercept + slope * s

writeRaster(gwr_pred,
            paste0(wd, "ntl_gwr.tif"),
            overwrite = TRUE)

When using multiple independent variables, I tried to stack them before I
convert them to spatialPoints, but then I don't know what to set in the
slope parameter.

-- 
Tziokas Nikolaos
Cartographer

Tel:(+44)07561120302
LinkedIn <http://linkedin.com/in/nikolaos-tziokas-896081130>

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