MFDataset not support NETCDF4

[legend0000]

[jswhit]

probably better to use xarray.mf_dataset anyway

[jswhit]

MFDataset really only requires the classic data model, so we could remove the check for the file format. The problem will be if NETCDF4 files are used that don't use the classic data model it may fail.

[legend0000]

I means "How to read NETCDF4 files by MFDataset ". Reading NETCDF4 files one by one is too slow!

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[jswhit]

I think we understood your meaning - xarray.mf_dataset has better functionality than netCDF4.MFDataset. xarray uses netCDF4 under the hood for netCDF file I/O.

[ChrisBarker-NOAA]

xarray does a lot that can be useful. Nonetheless, using the netCDF4 lib directly has a lot of use cases.

We are bitten a lot by this limitation -- netcdf4 is no longer rare, and is the default in most cases -- it seems we could remove this limitation pretty easily (at least for "classic" files -- and even for non-classic, probably be a bit smart about it :-)

Would a PR be accepted?

-CHB

[ChrisBarker-NOAA]

NOTE:

" if NETCDF4 files are used that don't use the classic data model it may fail."

what would cause it to fail? one thing I can think of is more than one unlimited dimension -- any others?

groups would be problematic, too.

But I think the code could check for the actual feature(s) that matter, rather than the file format, yes.

e.g. we commonly get a bunch o' netcdf4 files that we can't use with MFDAtaset, but we can simply convert them to netcdf3, and it all works -- so file format is not really the issue here, it's actual data layout and features..

or am I missing something?

[ChrisBarker-NOAA]

Ping! I'm happy to work on a PR -- but only if someone can tell me it has a chance of being accepted ....

@jswhit What do you think?