ncdisp displays the netcdf file but cannot open with netcdf.open

Hello,

I am using Matlab R2016a and trying to work with netcdf files. I can view the variable information with ncdisp and everything appears as I think it should, but I cannot used netcdf.open.

The output of ncdisp:

Format: classic

Dimensions: lon = 720 lat = 360 ncl2 = 365 Variables:

    lon           
           Size:       720x1
           Dimensions: lon
           Datatype:   single
           Attributes:
                       long_name = 'Longitude'
                       units     = 'degrees_east'
                       comment   = 'center of cell'
    lat           
           Size:       360x1
           Dimensions: lat
           Datatype:   single
           Attributes:
                       long_name = 'Latitude'
                       units     = 'degrees_north '
                       comment   = 'center of cell'
    O3_1hrDailyMax
           Size:       720x360x365
           Dimensions: lon,lat,ncl2
           Datatype:   single
           Attributes:
                       missing_value    = 1.000000020040877e+20
                       _FillValue       = 1.000000020040877e+20
                       average_op_ncl   = 'dim_avg_n over dimension(s): ncl_join'
                       lon              = 357.5
                       associated_files = 'baseURL: http://htap.icg.fz-juelich.de/data/ACCMIP gridspecFile: gridspec_atmos_fx_CESM-CAM-superfast_accrcp60_r0i0p0.nc'
                       cell_methods     = 'time: mean (interval: 30 minutes)'
                       original_name    = 'O3'
                       units            = '1'
                       long_name        = 'O3 Volume Mixing Ratio in Lowest Model Layer'
                       standard_name    = 'mole_fraction_of_ozone_in_air'
                       max_op_ncl       = 'dim_max_n over dimension(s): time'

The netcdf.open error:

Error using netcdflib

'ncid' must be a non-empty finite numeric scalar value.

Error in netcdf.getVar (line 100) data = netcdflib(funcstr,ncid,varid,varargin{1:end-1});

Error in tryingnetcdffiles (line 9) varid = netcdf.getVar('regrid_1hrDailyMaximum_CESM-CAM-superfast_accrcp60_r1i1p1_05x05.nc','lon','single');

Are there any ideas of things I should look into trying?

Thank you!

Answer 1

[Prashant Arora]

Hi MelMo,

It looks like the error is generated by the command "netcdf.getVar" function at line 9 of "tryingnetcdffiles" script/function. I see that you are calling the netcdf.getVar function with the name of the file rather than the file ID. To use the function, you need to first get the fileID by using netcdf.open like this:

ncid = netcdf.open('Name');
varname = netcdf.inqVar(ncid,0) %Query First Variable Name
varid = netcdf.inqVarID(ncid,varname) %Query ID with Variable Name
data = netcdf.getVar(ncid,varid);