Hi all,
I am looking into ways of aggregating NetCDF files programmatically for
a new version of ncWMS. The aim is to allow expressions such as "*.nc"
to result in a single dataset, so long as all NetCDF files share the
same variables/dimensions and differ only in the values on their time axes.
I can do this by writing an NcML file, but this is a bit of a hack, and
leaves files around. We previously did this by manually keeping track
of which time steps appeared in which files, but this doesn't easily fit
with our new data model, and seems unnecessary when there are several
Aggregation objects in the NetCDF-Java libraries which should be able to
do the job for us.
Searching lead me to this message on the list:
http://www.unidata.ucar.edu/mailing_lists/archives/netcdf-java/2013/msg00029.html
but unfortunately there were no responses. I was able to use the
AggregationUtil class from that post to read the correct metadata, but
like the person who posted I run into trouble when trying to actually
read the data. I get a slightly different stack trace, which starts:
java.io.IOException: BAD: missing spi: analysed_sst
at ucar.nc2.NetcdfFile.readData(NetcdfFile.java:1753)
at ucar.nc2.Variable.reallyRead(Variable.java:850)
...
and is then the same as in the other post.
I would be very grateful if anyone could suggest a way of making
aggregation work programatically, either with an adaptation of the above
method or something completely new.
Best Regards,
Guy Griffiths
--
Reading eScience Centre
