[R-sig-eco] Error in Kriging Procedure

[Alexandre F. Souza]

Hello,

I am new to interpolating techiques, and I am getting a persistent erro
message I have not been able to resolve. I am trying to krig spatialized
ordination scores into a raster of the Brazilian Atlantic Forest, as you
can see below. I previously run a NMDS with 5 dimensions on species
presence-absence data and saved the nmds scores. I send in attachment the
atlantic forest shapefile and the nmds scores, to make the code more
reproducible.

# Convert NMDS-scores to SpatialPoints objects
coords = as.data.frame(coords)
names(coords) = c("longitude","latitude")
nmds_scores<-cbind(coords, nmds_scores)
coordinates(nmds_scores)<-~longitude+latitude # Convert 'nmds_scores'
dataframe to SpatialPointsDataframe
wgs84<-"+proj=longlat +datum=WGS84 +no_defs +ellps=WGS84 +towgs84=0,0,0" #
WGS84 Coordinate Reference System (CRS)
crs(nmds_scores)<-wgs84 # Set the original CRS (WGS84)
new_crs<-"+proj=robin +lon_0=0 +x_0=0 +y_0=0 +a=6371000 +b=6371000 +units=m
+no_defs" # Transform CRS to Robinson projection (it is necessary to have
projected data for interpolation)
nmds_scores<-spTransform(nmds_scores, new_crs)


# Read the shapefile of Brazilian Atlantic Forest (BAF) and rasterize it
BAF_limit<-readOGR("C:/Users/Augusto/Documents/MESTRADO/Projeto
CAATINGA/Analise k-means/shapecaa")
BAF_limit<-spTransform(BAF_limit, wgs84) # Change the CRS from SIRGAS2000
to WGS84
r_ext<-extent(BAF_limit)
r<-raster() # Create a empty raster to receive data
res(r)<-0.04166667 # Define raster resolution in decimal degrees (= 10
arc-min)
r<-crop(r, r_ext) # Define spatial extent of the raster (same as BAF)
BAF_raster<-rasterize(BAF_limit, r, field=1, background=NA)

# Get the spatial coordinates of BAF pixels
get_coords<-rasterToPoints(BAF_raster)
get_coords<-as.data.frame(get_coords[, c(1:2)])
get_coords<-cbind(get_coords, NA, NA, NA)
names(get_coords)<-c("longitude", "latitude", "NMDS1", "NMDS2", "NMDS3")
coordinates(get_coords)<-~longitude+latitude # Convert 'get_coords'
dataframe to SpatialPointsDataframe
crs(get_coords)<-wgs84 # Set the original CRS (WGS84)
get_coords<-spTransform(get_coords, new_crs) # Transform CRS to Robinson
projection

gModel_ok <- gstat(NULL, id='NMDS1_kri',
                   formula= NMDS1 ~ 1,
                   locations=coords, model=data.fit)

G0y_ok <- interpolate(BAF_raster, gModel_ok, xyOnly=FALSE)

Error in as(data, "data.frame") :
  no method or default for coercing “NULL” to “data.frame”


Do anyone has any idea of what may be wrong? I tried to empty the raster
changing all vaues to zero but did not work.

Thanks a log in advance,

Alexandre
-- 
Dr. Alexandre F. Souza
Professor Adjunto IV
Chefe do Departamento de Ecologia
Universidade Federal do Rio Grande do Norte
CB, Departamento de Ecologia
Campus Universitário - Lagoa Nova
59072-970 - Natal, RN - Brasil
lattes: lattes.cnpq.br/7844758818522706
http://www.esferacientifica.com.br
http://www.docente.ufrn.br/alexsouza
orcid.org/0000-0001-7468-3631 <http://www.docente.ufrn.br/alexsouza>