[R] problem writing .bil files in netcdf
mdsumner at gmail.com
Fri Sep 2 17:09:43 CEST 2016
On Fri, 2 Sep 2016 at 00:43 Abdoulaye SARR <abdoulayesar at gmail.com> wrote:
> Dear List,
> I have daily rainfall data in .bil format and can get info of the file
> using rgdal:
> > library(rgdal)
> > GDALinfo("/1981/v2p19810101.bil")
> rows 1600
> columns 1500
> bands 1
> lower left origin.x -20
> lower left origin.y -40
> res.x 0.05
> res.y 0.05
> ysign -1
> oblique.x 0
> oblique.y 0
> driver EHdr
> projection NA
> How can I read all daily file and write them as netcdf files and
> concatenate as one yearly file and also avoid boundary pixels alter
> rainfall values.
You can read the single .bil and write it to NetCDF with raster (and the
rgdal and ncdf4) package:
r <- raster("/1981/v2p19810101.bil")
But, if you read in multi .bil files and build a multilayer raster, i.e.
st <- stack(list.files("/1981", pattern = "bil$", full.names = TRUE))
you *can* write it out to NetCDF, very similar to above with writeRaster,
but I think it will generate a variable (an netcdf array) for each layer.
To really write to .nc in a specific way you'll need to delve into the
standard tools in ncdf4, to create a file, create
variables/dimensions/attributes, and then populate the variable, in this
case probably one 3rd-level slice for each .bil. That might be better done
at the command line, say with nco (the "nc operators"). There are
copy-create idioms which is probably the way to go if you have a template
data file or CDF specification.
There may be some higher level tools in other packages on CRAN, check the
reverse depends/imports/suggests on CRAN for ncdf4. Also you should explore
RNetCDF which has an independent implementation.
(raster really blitzes the field in terms of high-level tools here, but it
has limits, with writing NetCDF *in specific ways* being one of them. GDAL
has similar limitations, since it sees the world in this
HTH, at least a little.
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> PLEASE do read the posting guide
> and provide commented, minimal, self-contained, reproducible code.
Dr. Michael Sumner
Software and Database Engineer
Australian Antarctic Division
203 Channel Highway
Kingston Tasmania 7050 Australia
[[alternative HTML version deleted]]
More information about the R-help