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How to create attribute of file?

Added by Liubov Tupikina over 11 years ago

Hi to all people!

I'm working with netcdf file and I need to create new attributes for one of my variables: "var1".
So that I have:
float var1(time, lat, lon) ;
var1:table = 255 ;
var1:grid_type = "gaussian" ;

I want to CREATE (not to change) variable attribute "long_name", so that I will have smth like this but for variable "var1":
float temp2(time, lat, lon) ;
temp2:long_name = "2m temperature" ;
temp2:units = "K" ;
temp2:code = 167 ;
temp2:table = 128 ;
temp2:grid_type = "gaussian" ;


Replies (3)

RE: How to create attribute of file? - Added by Ralf Mueller over 11 years ago

example: Lets use this files

netcdf zOld {
dimensions:
        x = 8 ;
        y = 8 ;
variables:
        double x(x) ;
                x:long_name = "x" ;
                x:actual_range = 0., 7. ;
        double y(y) ;
                y:long_name = "y" ;
                y:actual_range = 0., 7. ;
        float z(y, x) ;
                z:long_name = "z" ;
                z:_FillValue = NaNf ;
                z:actual_range = 719.896667480469, 1005.97003173828 ;

With the following call, you can add a new attribute the variable 'z'
ncatted -a newAtt,z,a,c,'newAttValue' zOld.nc -o zNew.nc

Now lets hava a look into zNew.nc
netcdf zNew {
dimensions:
        x = 8 ;
        y = 8 ;
variables:
        double x(x) ;
                x:long_name = "x" ;
                x:actual_range = 0., 7. ;
        double y(y) ;
                y:long_name = "y" ;
                y:actual_range = 0., 7. ;
        float z(y, x) ;
                z:long_name = "z" ;
                z:_FillValue = NaNf ;
                z:actual_range = 719.896667480469, 1005.97003173828 ;
                z:newAtt = "newAttValue" ;

If you leaf out the '-o' options, the changed will be applied to zOld.nc. Attributes can have different types like float or integers:
ncatted -a newFloatAtt,z,a,f,0.815 zOld.nc 
ncatted -a newIntAtt,z,a,i,34 zOld.nc

leads to
netcdf zOld {
dimensions:
        x = 8 ;
        y = 8 ;
variables:
        double x(x) ;
                x:long_name = "x" ;
                x:actual_range = 0., 7. ;
        double y(y) ;
                y:long_name = "y" ;
                y:actual_range = 0., 7. ;
        float z(y, x) ;
                z:long_name = "z" ;
                z:_FillValue = NaNf ;
                z:actual_range = 719.896667480469, 1005.97003173828 ;
                z:newFloatAtt = 0.815f ;
                z:newIntAtt = 34 ;

RE: How to create attribute of file? - Added by Neil Brink over 11 years ago

Thanks for your reply. I think this is easy as compared to another solution I had considered. I think I will go with this only.
http://www.karinherzog.com/de

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