Scale factor and offset problem

[Didier Earith]

Hi John


Thanks for you answer.

In some cases, I need  to unpack and repack data, because I need to extract 
data according to user's crtiteria, among others, data value ( ie 
temperature between  10 and 30).

I use NetcdfDataset.acquireDataset() for performance as described in 
documentation.

I also could use NetcdfDataset.openDataset() with "enhance" parameter set 
to false, but  I need to add Coordinate Systems, that's also why I use the 
"enhance" flag to true (acquireDataset() or openDataset()).

Didier



At 18:05 19/06/2007, John Caron wrote:
>Hi Didier:
>
>Is there some reason to unpack and repack?
>
>If you open with NetcdfDataset.openFile() it will not get unpacked - you 
>will have the original variable and data.
>
>John
>
>Didier Earith wrote:
>>Hi all,
>>I have a problem with scale factor and offset when I use th netcdf java 
>>API (v2.2.20).
>>I have to extract netcdf variables with scale_factor and offset 
>>attributes and write the results as another netcdf file.
>>The NetcdfDataset class automatically deals with scale_factor and offset 
>>attributes when it opens dataset, and that's right (but it removed 
>>scale_factor and add_offset attributes)
>>But when I want to write variables into another netcdf file, I need to 
>>have the data type, the scale factor and offset values of the original 
>>variables to packed data again.
>>The VariableDS class provides a public getOriginalDatatype API, that's OK.
>>But scale factor and offset attribute of the VariableDS class are private 
>>and there is no API get them.
>>I saw the getOriginalVariable in the VariableDS class which return the 
>>original variable with the scale_factor and add_offset attributes. But 
>>unfortunately, this API is not visible (private) :
>>  ucar.nc2.Variable getOriginalVariable() {
>>     *return* orgVar; // proxy.getOriginalVariable();
>>   }
>>So, how can I get the scale factor and offset values with netcdf java API 
>>to pack again the variables.
>>Didier.
>>
>>
>
>
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