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Impossible to set a dimension with size=0 #1480
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The python interface does not allow to create dimensions with value=0, as they will be interpreted as unlimited.
It would be nice to enable the possibility to set a dimension with size 0; with C/C++ interface this is possible
Activity
jswhit commentedon Apr 25, 2026
I don't think we can change this now without potentially breaking a lot of code. Curious what the use case is? Note that you can create scalar variables by using an empty tuple for the dimension argument in createVariable.
davide-f commentedon Apr 27, 2026
In smspp-project, a tool for optimization, we have indices that may be empty and as such indexed over a 0-valued index.
What about adding an optional argumwnt such as enable_unlimited
X.createDimension(name, value=None, enable_unlimited=True)
Such that when enable_unlimited is false, 0 is treated as number?
This is back compatible. I understand the behavior must not change given usage
jswhit commentedon Apr 27, 2026
I think a dimension with size 0 is technically not allowed in netcdf unless the dimension is unlimited (the NC_UNLIMITED size argument is set to 0 in netcdf.h).
Dave-Allured commentedon Jul 31, 2026
@davide-f I do not think this is possible, even with the C/C++ interface. My understanding is that this would contradict the netCDF data model, which requires all dimensions be non-zero for fixed-size variables. My understanding is that the netcdf-C library enforces this. Size zero is supported only for unlimited dimensions, as you noted.
If you do not agree, would you please show a minimal example in C?