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NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
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You can also try the -s option from ncdump, which will tell you about chunking and compression for each variable. If chunking is too small, for example, then compression will be limited. (I'm a few versions behind, but I assume that '-s' is still there.) -- Ted On Dec 17, 2013, at 2:55 PM, Frank Fuchs wrote: > Sorry I did not mentioned that the installation included hdf5 and zlib (I > think one has to disable the explicitly - otherwise). > Thank you for the ncdump option - I was looking for something like this to > check at least that I'm writing Netcdf4 files now. > Indeed ncdump -k gives me "netCDF-4". - So compression is supposed to work, > not? > > Regards, > Frank > > > > > > > 2013/12/17 Nick Papior Andersen <nickpapior@xxxxxxxxx> > You do not specify whether you have compiled with hdf5 and zlib? > If you haven't specified this at compile time, you don't have compression > enabled and you need to install hdf5 and zlib (at least). > > You can test your file by this: > ncdump -k <file> > '1' or 'classic' => netcdf classic format > '2', '64-bit-offset', or '64-bit offset' => netCDF 64-bit format > '3', 'hdf5', 'netCDF-4', or 'enhanced' => netCDF-4 format (enhanced data > model) > '4', 'hdf5-nc3', 'netCDF-4 classic model', or 'enhanced-nc3' => netCDF-4 > classic > model format > > What you want is 3 or 4 (as I remember, a netcdf3 installation from a netcdf4 > source would only allow k=1 or k=2). > > Kind regards Nick > > 2013/12/17 Frank Fuchs <fk.fuchs@xxxxxxxxxxxxxx> > Hi, > > I managed to compile netcdf-4.3.0 using mingw-w64 gcc 4.8.1. > All I had to disabale was DAP (I have no use for anyway). > > I tested that I can read and write netcdf files using the newly build .dll > Now I wanted to test compression using the cxx4 interface, enabling it by > ncvar_data.setCompression(true,true,1) for the heaviest of my variables. > > However, even for a file filled with constants the files remain as big as > before. > Further tests using nccopy -d9 old.nca new.nca did not result in a > modification of the file size. > > Any advise? > > Best, > Frank > > > > _______________________________________________ > netcdfgroup mailing list > netcdfgroup@xxxxxxxxxxxxxxxx > For list information or to unsubscribe, visit: > http://www.unidata.ucar.edu/mailing_lists/ > > > > -- > Kind regards Nick > > _______________________________________________ > netcdfgroup mailing list > netcdfgroup@xxxxxxxxxxxxxxxx > For list information or to unsubscribe, visit: > http://www.unidata.ucar.edu/mailing_lists/
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