NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
Current content can be found at unidata.ucar.edu.

To learn about what's going on, see About the Archive Site.

Re: [netcdfgroup] attributes not showing up when reading openDAP datasets

  • To: Jeff Whitaker <jswhit@xxxxxxxxxxx>
  • Subject: Re: [netcdfgroup] attributes not showing up when reading openDAP datasets
  • From: "Arthur M. Greene" <amg@xxxxxxxxxxxxxxxx>
  • Date: Thu, 10 Sep 2009 10:29:00 -0400
One addendum: This is (or should be) a password-protected server. I'm not sure how attempting to access it without a userid and password might modify what is returned, but I do have a password, and fetching the data using the appropriately modified url yields a time variable that does have _some_ defined attributes. There are no units or calendar, however, and other attributes could also be missing (like bounds). I see 

In [22]: dir(timedata)
Out[22]: ['__class__', '__delattr__', '__delitem__', '__doc__', '__getattr__', '__getattribute__', '__getitem__', '__hash__', '__init__', '__len__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__setitem__', '__str__', '_assign_vlen', '_get', '_grpid', '_iscompound', '_isprimitive', '_isvlen', '_nunlimdim', '_put', '_varid', 'assignValue', 'chunking', 'dimensions', 'dtype', 'endian', 'filters', 'getValue', 'group', 'maskandscale', 'ncattrs', 'ndim', 'set_auto_maskandscale', 'shape', 'size'] 

In [25]: print timedata.shape
(1680,)
In [26]: print timedata.size
1680
In [29]: print timedata.ndim
1
In [30]: print timedata.dtype
float64
In any event, it seems that not all the attributes are being read. My system: 

netCDF4-0.8.2.tar.gz
curl-7.19.6.tar.gz
netcdf-4.1-beta2.tar.gz
hdf5-1.8.3-snap2.tar.gz
all installed according to instructions here: http://netcdf4-python.googlecode.com/svn/trunk/docs/netCDF4-module.html 

OS is RedHat Enterprise Linux 5.

One last detail: I can't access the data itself:

In [32]: tas = datobj.variables['tas']

In [33]: tas.shape
Out[33]: (1680, 90, 144)

In [34]: testdat = tas[0,:,:]
---------------------------------------------------------------------------
RuntimeError                              Traceback (most recent call last)

/home/amg/work/nhmm/<ipython console> in <module>()
/home/amg/usr/local/cdat/trunk/lib/python2.5/site-packages/netCDF4.so in netCDF4.Variable.__getitem__ (netCDF4.c:14286)()
/home/amg/usr/local/cdat/trunk/lib/python2.5/site-packages/netCDF4.so in netCDF4.Variable._get (netCDF4.c:18945)() 

RuntimeError: NetCDF: Variable has no data in DAP request

-----------------------

Thanks much for following up on this.

Best,

Arthur


Jeff Whitaker wrote:


Dennis:  If I open
http://esgcet.llnl.gov/dap/ipcc4/20c3m/gfdl_cm2_1/pcmdi.ipcc4.gfdl_cm2_1.20c3m.run1.atm.mo.xml
with netcdf-4.1-beta2, then get the time variable, it appears there are no attributes associated with it. Browsing the xml file
http://esgcet.llnl.gov/aggregates/ipcc4/20c3m/gfdl_cm2_1/pcmdi.ipcc4.gfdl_cm2_1.20c3m.run1.atm.mo.xml
it does appear these attributes are defined, but somehow the client is not getting them.
Is it a bug in the way there are serving the data, or a bug in the opendap client in netcdf-4.1? 

-Jeff


--
*^*~*^*~*^*~*^*~*^*~*^*~*^*~*^*~*^*~*^*~*^*~*^*~*^*~*^*~*^*~*^*~*
Arthur M. Greene, Ph.D.
The International Research Institute for Climate and Society
The Earth Institute, Columbia University, Lamont Campus
Monell Building, 61 Route 9W, Palisades, NY  10964-8000 USA
Tel: 845-680-4436    | Fax: 845-680-4864
amg@xxxxxxxxxxxxxxxx | http://iri.columbia.edu
*^*~*^*~*^*~*^*~*^*~*^*~*^*~*^*~*^*~*^*~*^*~*^*~*^*~*^*~*^*~*^*~*

begin:vcard
fn:Arthur M. Greene
n:Greene;Arthur M.
email;internet:amg@xxxxxxxxxxxxxxxx
tel;work:845-680-4436
tel;fax:845-680-4865
x-mozilla-html:FALSE
version:2.1
end:vcard
  • 2009 messages navigation, sorted by:
    1. Thread
    2. Subject
    3. Author
    4. Date
    5. ↑ Table Of Contents
  • Search the netcdfgroup archives: