Dear Martin I feel there would be an advantage in flexibility, by not requiring the missing data count to be the first bin necessarily. The new attribute could indicate the index of the bin which contains the missing data count. I suggest that this would be an attribute of the coordinate variable of the histogram for the quantity which is binned (cloud top height), since the index refers to that dimension specifically.
I agree it would be neat if it were possible instead to put _FillValue in the coordinate variable. Actually _FillValue is not allowed in coordinate vars by CF, so as far as CF is concerned it would not be a problem to adopt this as a new convention. But maybe software would have problems with it. If we need the new attribute, I'd suggest missing_value_index, to make it more similar to missing_value and _FillValue. What would you put in the coordinate and bounds for the missing data bin? In any case, this needs a new convention to be proposed as a trac ticket. Best wishes Jonathan ----- Forwarded message from [email protected] ----- > Date: Tue, 11 Oct 2016 12:41:21 +0000 > From: [email protected] > To: [email protected] > CC: [email protected] > Subject: [CF-metadata] Missing data bins in histograms > > Hello, > > the CF standard name list has two "histogram_.... " entries, and in the CMIP6 > data request we may need to add a third, a histogram_of_cloud_top_height. > Besides the standard name, we also need, for this new variable, a method of > encoding the "missing data" bin in the histogram. That is, the histogram > should record frequency in 16 data bins and one additional bin for the > frequency of missing data. > > Can we define a "missing_data_index" attribute for histogram variables, and > use this to indicate that the first bin in the array has this special > purpose. It might be more pythonic to put the _FillValue in the coordinate > value for the missing data bin, but I suspect that this would cause > substantial problems for many software packages. > > regards, > Martin > _______________________________________________ > CF-metadata mailing list > [email protected] > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata ----- End forwarded message ----- _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
