This is might help you: https://zia207.github.io/geospatial-r-github.io/netCDF-data-processing.html
Zia On Wed, Mar 18, 2020, 9:34 AM Frederico Faleiro <fvfale...@gmail.com> wrote: > Hi Miluji, > > the R in general do not handle very well with netCDF. However I > recommend you use the netcdf4 package before try others. > This link is a good start: > > http://geog.uoregon.edu/bartlein/courses/geog490/week04-netCDF.html#get-coordinate-including-time-variables > . > The coordinates of this file is not in longitude and latitude, it use > "number_of_lines" for X Axis and "number_of_pixels" for Y Axis. This way > the difference between the cells is always one and raster package > interprete the difference as one degree and return an warning about it. > I open the file in the software Panoply (design to work with netCDF) and > everything is OK apparently. > Check bellow some exploration of the data in R. > > library(raster) > library(ncdf4) > library(rgdal) > > # netcdf4 package > netcdf_file <- "VNP02DNB_NRT.A2020069.1048.001.nc" > nc <- nc_open(netcdf_file) > print(nc) > # check your variable is structured as: > observation_data/DNB_observations[number_of_pixels,number_of_lines] > # variables available > names(nc[["var"]]) > # properties from your variable > ncatt_get(nc, "observation_data/DNB_observations") > # get the variables values and check the structure > obs_matrix <- ncvar_get(nc, "observation_data/DNB_observations") > str(obs_matrix) > > # raster package > nc_r <- brick(netcdf_file, lvar=0, values=TRUE, > varname="observation_data/DNB_observations") > # [1] "vobjtovarid4: **** WARNING **** I was asked to get a varid for > dimension named number_of_pixels BUT this dimension HAS NO DIMVAR! Code > will probably fail at this point" > # [1] "vobjtovarid4: **** WARNING **** I was asked to get a varid for > dimension named number_of_lines BUT this dimension HAS NO DIMVAR! Code will > probably fail at this point" > > Best regards, > > Frederico Faleiro > Postdoctoral Researcher in the INCT-EECBio (https://www.eecbio.ufg.br/) > Federal University of Goiás | Brazil > RG: https://www.researchgate.net/profile/Frederico_Faleiro > > On Tue, Mar 17, 2020 at 11:39 AM Miluji Sb <miluj...@gmail.com> wrote: > > > Dear all, > > > > Hope everyone is keeping safe. > > > > I am trying to extract/read VIIRS nighttime lights data but the output > > seems rather strange. > > > > I have uploaded the file here > > <https://drive.google.com/open?id=1zpqXJ8AlEcnk6ApRb75tfQc4-Y8AfK5h> so > as > > not exceed the size limit of the email. > > > > ## Code ## > > library(ncdf4) > > library(rgdal) > > > > netcdf_file <- c("VNP02DNB_NRT.A2020069.1048.001.nc") > > nl <- brick(netcdf_file, lvar=0, values=TRUE, > > varname="observation_data/DNB_observations") > > > > ## Detail ## > > class : RasterLayer > > dimensions : 3232, 4064, 13134848 (nrow, ncol, ncell) > > resolution : 1, 1 (x, y) > > extent : 0.5, 4064.5, 0.5, 3232.5 (xmin, xmax, ymin, ymax) > > crs : NA > > source : C:/Users/shour/Desktop/VNP02DNB_NRT.A2020069.1048.001.nc > > names : DNB.observations.at.pixel.locations > > zvar : observation_data/DNB_observations > > > > The spatial resolution is supposed to be 750m but this shows 1°. What am > I > > doing wrong? Any help will be greatly appreciated. Thank you. > > > > Sincerely, > > > > Millu > > > > [[alternative HTML version deleted]] > > > > _______________________________________________ > > R-sig-Geo mailing list > > R-sig-Geo@r-project.org > > https://stat.ethz.ch/mailman/listinfo/r-sig-geo > > > > [[alternative HTML version deleted]] > > _______________________________________________ > R-sig-Geo mailing list > R-sig-Geo@r-project.org > https://stat.ethz.ch/mailman/listinfo/r-sig-geo > [[alternative HTML version deleted]] _______________________________________________ R-sig-Geo mailing list R-sig-Geo@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-geo