h5netcdf writes invalid netcdf to existing netcdf files about h5netcdf

[shoyer]

• remove _NCProperties when appending invalid netcdf data to an existing file

This solution sounds good to me!

[kmuehlbauer]

It looks like this behavior is there for a very long time.

There are at least two solutions to this problem:

• do not allow appending invalid netcdf data to a NetCDF4 conforming file (having _NCProperties), allow only newly created files with invalid netcdf data (they will miss the _NCProperties
• remove _NCProperties when appending invalid netcdf data to an existing file

As writing of invalid netcdf data can only happen if invoked with invalid_netcdf=True the users should know what they are doing so I would go for the second approach removing an existing _NCProperties.

@shoyer It would be great if you could share your thoughts on that issue.

[kmuehlbauer]

Please have a look at a possible fix in #166.

We do not write _NCProperties when creating a file from scratch with invalid netcdf features. So it is fitting to assume that we should remove _NCProperties when writing invalid netcdf features to an existing (valid) file.

As users might still use .nc extension when writing invalid netcdf features a UserWarning is displayed:

UserWarning: You are writing invalid netcdf features to file test.nc. The file will thus be not conforming to NetCDF-4 standard and might not be readable by other netcdf tools. Consider using a different extension.

[kmuehlbauer]

I've opened a discussion over at unidata: How does netcdf-c recognize netCDF4 format.

[kmuehlbauer]

Thanks Stephan, much appreciated.

[kmuehlbauer]

fixed in #166