Really simple problem with the raster package, also using ncdf4 to load in an ECMWF Era-Interim Netcdf file.
Simply doing this:
a <- nc_open("SSTs.nc") B <- brick(a, varname="sst")
Returns this:
Error in (function (classes, fdef, mtable) : unable to find an inherited method for function ‘brick’ for signature ‘"ncdf4"’
The file is just SST data over the whole globe, for 1 month (Jan2016). When I convert it into an array (i.e. extract dimensions/variable, and convert time to UTC, shove it into an array) I don't get the same error, but the raster package says it supports .nc files straight in (so long as they're cf-1 compatible, which Era-Interim .nc's are)
Any help much appreciated, have tried this with many Netcdf files (non-Era Interim too).
thank Renaud Lancelot, who give clearly source code. I have modified his code to fit with your data
# load package library(sp) library(raster) library(ncdf4) # read ncdf file nc<-nc_open('D:/SSTs.nc') # extract variable name, size and dimension v <- nc$var[[1]] size <- v$varsize dims <- v$ndims nt <- size[dims] # length of time dimension lat <- nc$dim$latitude$vals # latitude position lon <- nc$dim$longitude$vals # longitude position # read sst variable r<-list() for (i in 1:nt) { start <- rep(1,dims) # begin with start=(1,1,...,1) start[dims] <- i # change to start=(1,1,...,i) to read timestep i count <- size # begin with count=(nx,ny,...,nt), reads entire var count[dims] <- 1 # change to count=(nx,ny,...,1) to read 1 tstep dt<-ncvar_get(nc, varid = 'sst', start = start, count = count) # convert to raster r[i]<-raster(dt) } # create layer stack with time dimension r<-stack(r) # transpose the raster to have correct orientation rt<-t(r) extent(rt)<-extent(c(range(lon), range(lat))) # plot the result spplot(rt)
