?Dear R colleagues,
?Currently, I am working with the vegetation map published by SAGE
(http://www.sage.wisc.edu/download/potveg/global_potveg.html). This map is
published in netcdf and I can easily load it into R using the package
"raster".
?But I have found another vegetation map (also netcdf, same resolution)
which is more realistic to my work region. Thus, what I need to do is
overlay the two maps, but using a clip feature (i.e. a shapefile of South
America) as a delimiter to this operation, in order to capture the
information of the newest map.
?I am trying to use the "overlay" function of raster package, but
apparently it isn't possible (or I am missing something) to use a clip
feature to restrain the spatial domain of the operation.
?Any tips on how to do this? Below is the code I am using.
?Best wishes,
?Thiago Veloso.
#Loading required packages
library(raster)
library(maptools)
#Loading SAGE vegetation map
vegmap<-raster("C:/temp/vegmap_ibis/data/vegtype.nc")
#Loading new vegetation map
new_vegmap<-raster("C:/temp/vegmap_ibis/data/new_vegtype.nc")
#Loading SA shapefile
south_america<-readShapePoly("C:/temp/vegmap_ibis/shapes/southamerica.shp")
#Replacing the original map with the modified one
result<-overlay(vegmap,new_vegmap,fun=function(x){x}) #this is where I
stop - I don't know how to use the shapefile as a clip feature in this
function...