dtcenter/MET

Enhance MET to parse the `set_attr` options prior reading data from gridded data files

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JohnHalleyGotway commented

Describe the Enhancement

This enhancement request arose via GitHub discussion dtcenter/METplus#2507. The user provided a NetCDF file where the grid information is formatted in a way that MET does not expect. The set_attr options, including set_attr_grid are provided to enable the user to override the metadata defined in the input gridded data files. However, the current order of processing logic makes them less useful than they could be.

Please see a sample input file in seneca:/d1/projects/METplus/discussions/2507/phyf000.nc. Running this through plot_data_plane with file_type=NETCDF_NCCF; produces this error message:

ERROR  : NcCfFile::read_netcdf_grid() -> Couldn't figure out projection from information in netCDF file.

Adding the set_attr_grid option to explicitly define the grid for the data still produces the same error message.

This issue is to update the processing logic for reading data from gridded input file. Currently, MET opens the file, parses the metadata, and then updates the metadata based on the set_attr options. If errors are encountered when parsing the metadata from the file, MET exits with bad status prior to handling the set_attr options. Modify this logic so that if set_attr options are defined, the code doesn't even try to parse that metadata from the file.

Of course, such data could also be handled via Python embedding. But supporting it via the set_atttr options may be easier for some users.

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3 days?

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hsoh-u commented

Grid definition does not include the north to south latitude. How about using the negative dy value to swap data for north to south?

hsoh-u commented

This was fixed by Enhance the set_attr_grid processing logic.

The grid definition of rotlatlon:

rotlatlon Nx Ny lat_ll lon_ll delta_lat delta_lon true_lat_sp true_lon_sp aux_rotation

Here is a command with set_attr_grid at seneca:

/d1/projects/MET/MET_regression/develop/NB20241108/MET-develop/bin/plot_data_plane  \
  /d1/projects/METplus/discussions/2507/phyf000.nc test.ps \
  'name="ext550"; level="(0,64,*,*)"; file_type=NETCDF_NCCF; set_attr_grid="rotlatlon 4881 2961 -37.0 299.0 0.025 0.025 -35.0 247.0 0.0";' \
  -v 4

This produce the same plot by python embedding at dtcenter/METplus#2507