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[Support #KTC-439068]: writing netCDF files using netCDF java

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  • Subject: [Support #KTC-439068]: writing netCDF files using netCDF java
  • Date: Mon, 10 Dec 2007 10:30:35 -0700
Hi Rajesh,

The Grid/ARRAY/MAPS terminology is part of the OPeNDAP data access protocol. In 
netCDF, the ARRAY corresponds to an n-dimensional variable and the MAPS 
correspond to the coordinate variables for those n-dimensions. The OPeNDAP 
server knows about netCDF coordinate variables and maps the data and coordinate 
variables into its Grid/ARRAY/MAPS data type.

The "Writing NetCDF Files: Best Practices" document is really good and has a 
section on coordinate variables that might be useful. Here's the URL for the 
document:

http://www.unidata.ucar.edu/software/netcdf/docs/BestPractices.html

The reason you see Grid/ARRAY/MAPS for the below listing is because the dataset 
contains lat/lon coordinate variables and each data array uses the 
corresponding dimensions. The reason the URL you give below does not have 
Grid/ARRAY/MAPS is because there are no coordinate variables.

Hope that helps,

Ethan

> I am a graduate student at UIUC and working with NCSA for a project. For
> the project I was trying out netCDF java library and have run into a
> confusion. I am trying to write some point observation data which has
> lat, lon and time as dimensions. The data set that I get is something
> like:
> 
> Dataset {
> Float32 lat[lat = 1];
> Float32 lon[lon = 1];
> Grid {
> ARRAY:
> Float64 height[lat = 1][lon = 1];
> MAPS:
> Float32 lat[lat = 1];
> Float32 lon[lon = 1];
> } height;
> Grid {
> ARRAY:
> Int32 discharge[lat = 1][lon = 1];
> MAPS:
> Float32 lat[lat = 1];
> Float32 lon[lon = 1];
> } discharge;
> Grid {
> ARRAY:
> Float64 precipitation[lat = 1][lon = 1];
> MAPS:
> Float32 lat[lat = 1];
> Float32 lon[lon = 1];
> } precipitation;
> } testAll/USGS_xy.nc;
> 
> 
> The thing that puzzles me is why I am getting 'Grid',"ARRAY","MAPS" in the 
> data. What makes the data type Grid here?
> Why dataset like this:
> http://motherlode.ucar.edu:8080/thredds/dodsC/station/profiler/wind/06min/20071206/PROFILER_wind_06min_20071206_2342.nc.html
> 
> doesn't have GRID etc?
> 
> Thanks a lot for your cooperation.
> 
> 
> regards,
> rajesh
> 
> 


Ticket Details
===================
Ticket ID: KTC-439068
Department: Support netCDF Java
Priority: Normal
Status: Open