Hi Gaby,
I am new to NetCDF format, so please bear with me...
When I currently instantiate an array it
zeros out all entries, is there a way to avoid that? I don't see
anything in the javadocs that allows me to do this.
When I write out the array to a file, what I'd like to see in the output
file when I invoke ncdump is entries like _, _, _, ... where there is
no data.
I guess this must be something to do with fill mode and the value of
_FillValue. How are you creating the file? if
NetcdfFileWriteable.createNew() or openExisting() what fill mode are you
using? With fill mode enabled the array should get pre-filled with
whatever '_FillValue' is set to for the variable in question. If you
don't want this behavior then set fill mode to false.
according to ncdump man page:
ncdump uses ‘_’ to represent data values that are equal to the
_FillValue’ attribute for a variable, intended to represent data
that has not yet been written. If a variable has no ‘_FillValue’
attribute, the default fill value for the variable type is used if the
variable is not of byte type.
I would infer from that that if you do want '_' used to represent
missing data then you need fill mode enabled. Further the _FillValue
used will have to match ncdump's defaults (or be stated explicitly in
your netCDF file).
I'm not sure what NJ22 uses as default _FillValues (NaN for floats?, not
sure about ints), but it is possible that NJ22's defaults do not match
ncdump's expected values (being the C defaults defined in netcdf.h, I
assume).
Better practice might be to explicitly define a fill value outside the
valid range for your data and add the _FillValue attribute to the
variable. That way ncdump should always recognise it whatever value you
use.
Hope this helps
Simon
--
Simon Wood
Scientific Programmer (Remote Sensing)
National Institute of Water and Atmospheric Research, Wellington, NZ
simon.wood@xxxxxxxxxx
http://www.niwa.co.nz
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