[Gerrit Holl]
>> I am moving from NetCDF to HDF5. In NetCDF, I can assign attributes to
>> each variable/column. That is very useful for self-documenting the
>> file like this:
>>
>> double AVHRR_LONG(Collocations) ;
>> AVHRR_LONG:long_name = "AVHRR Longitude" ;
>> AVHRR_LONG:units = "degrees_east" ;
>> AVHRR_LONG:valid_range = -180., 180. ;
>>
>> I know that in HDF5, I can assign attributes to each node. But I think
>> the columns of a table are not nodes. Is there an equivalent in HDF5
>> to NetCDF's variable attributes? How would I use this in pytables?
[Jeff Whitaker]
> Gerrit: Are you aware that if you use netcdf 4, then your data is
> actually saved in an HDF5 file (readable by hdf5 and netcdf clients)?
A bit, but I don't understand the details of it. I should specify that
I was using NetCDF 3 before.
But then how would I use all of pytables' nice HDF5 features (blosc
compression, fast searching, possibly indexing if I buy the
professional version) in a NetCDF4 file? Some combination of your
netcdf4-python with pytables?
[David E. Sallis]
> You can store arbitrary key/value pairs on a node by using the node's
> _f_setAttr() method. I use this frequently and in much the same way as in
> your
> example. The key is the column name, and the value is a Python dictionary
> containing the long name, units, etc.
>
> Example: n._f_setAttr('AVHRR_LONG':{'long_name':'AVHRR_Longitude',
> 'units':'degrees_east', 'valid_range':(-180.0,180.0)})
What is 'n' in this case? The table containing those columns? So then
I actually set the properties to the table, with property names equal
to the column, rather than setting properties to the variable, or am I
misunderstanding things?
Gerrit.
--
Gerrit Holl
PhD student at Department of Space Science, Luleå University of
Technology, Kiruna, Sweden
http://www.sat.ltu.se/members/gerrit/
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