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RNetCDF: retrieving variable names and units

3 messages · Jannis, David W. Pierce, Michael Sumner

Jannis
# 
Dear List,


does anybody has experience with the RNetCDF package? I manage to open a connection and copy data from a ncdf file but would need a way to automatically retrieve variable names (ideally all of them from one file) and units from the file.


Any ideas?
Jannis
David W. Pierce
# 
Hi Jannis,

although I don't know how you'd do that with RNetCDF, with the ncdf
package it's pretty easy:

ncid = open.ncdf( 'file.nc' )
nvars = ncid$nvars
for( ivar in 1:nvars )
    print(paste("var number",ivar,"is named", ncid$var[[ivar]]$name, "and
has units", ncid$var[[ivar]]$units ))

Regards,

--Dave
Jannis wrote:
-------------------------------------------------------------------
David W. Pierce
Division of Climate, Atmospheric Science, and Physical Oceanography
Scripps Institution of Oceanography
(858) 534-8276 (voice)  /  (858) 534-8561 (fax)    dpierce at ucsd.edu
Michael Sumner
# 
There are a number of functions in the package to inquire about the
file contents. See library(help = RNetCDF).

For example:

library(RNetCDF)

nc <- open.nc("file.nc")

var.inq.nc(nc, 0)
$id
[1] 0

$name
[1] "longitude_U"

$type
[1] "NC_DOUBLE"

$ndims
[1] 1

$dimids
[1] 1

$natts
[1] 0

You can then read from the file with something like this:

obj0 <- var.inq.nc(nc, 0)
dat <- var.get.nc(nc, obj0$name, start = ...)

Going with ncdf or ncdf4 package is probably better ( I just happen to
be more familiar with RNetCDF.)

Cheers, Mike.
On Thu, Jan 13, 2011 at 9:00 AM, Jannis <bt_jannis at yahoo.de> wrote: