redcuing netCDF to only non-zero values.
Added by Sondre Bekken over 5 years ago
Dear,
I am wondering if it is possible to reduce the gridsize of a netCDF to only exist of the values with non-zero numbers and cut out the values that are zero?
If so how is it done?
Kind regards
Sondre
Replies (6)
RE: redcuing netCDF to only non-zero values. - Added by Sondre Bekken over 5 years ago
I manage to figure it out. Used cdo ifthen infile infile outfile.
RE: redcuing netCDF to only non-zero values. - Added by Ralf Mueller over 5 years ago
Sondre,
could you prove some sample data and one or two CDO calls? this would be very helpful to understand your solution.
thx in advance
ralf
RE: redcuing netCDF to only non-zero values. - Added by Sondre Bekken over 5 years ago
I was not able to reduce the gridsize, but only adding more missing data.
I did this:
cdo ifthen northsea.nc northsea.nc nonzeronorthsea.nc
This made all the 0 values to NaN and where not added when I plotted the file in panoply(which is a mapping program).
Hope this is helpful!
Kind regards,
Sondre
northsea.nc (196 KB) northsea.nc | |||
nonzeronorthsea.nc (197 KB) nonzeronorthsea.nc |
RE: redcuing netCDF to only non-zero values. - Added by Ralf Mueller over 5 years ago
didn't look into your data, yet. But I think the operators reducegrid
might be what your are looking for. There is a special post about it: https://code.mpimet.mpg.de/boards/53/topics/3895
hth
ralf
RE: redcuing netCDF to only non-zero values. - Added by Karin Meier-Fleischer over 5 years ago
Hi Sondre, hi Ralf,
just to mention that you can use
cdo -f nc -setctomiss,0 northsea.nc nonzeronorthsea_miss.nc
The output of reducegrid is an unstructured grid which can't be diplayed by Panoply.
-Karin
RE: redcuing netCDF to only non-zero values. - Added by Ralf Mueller over 5 years ago
A more general remark: If you want to reduce the gridsize, you should be aware of the fact, that the grid is constant for all timesteps. In case of a time-varying number of missing values (or zeros) this will not be possible. And CDO does not support time dependent grids - nor do I know any other tool, that does.
So it depends what your plan was: reducing file size? avoid handling of missing values in your program?