issue_comments: 991042526

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https://github.com/pydata/xarray/issues/6055#issuecomment-991042526 https://api.github.com/repos/pydata/xarray/issues/6055 991042526 IC_kwDOAMm_X847Ehve 3383837 2021-12-10T14:59:29Z 2021-12-10T15:25:11Z CONTRIBUTOR

@dcherian Chiming in as the author of TileDB-Inc/TileDB-CF-py#117. To help ensure the tiledb backend matches the behavior of xr.open_dataset for netCDF files, can you help me understand why the promotion to float does NOT occur in the following case:

``` import netCDF4 import xarray as xr import numpy as np

filename = 'temp_file.nc' with netCDF4.Dataset(filename, mode="w") as group: group.createDimension("index", 4) var = group.createVariable("var", np.int16, ("index",)) var[0:3] = np.array([5, 6, 7], dtype=np.int16) dataset = xr.open_dataset(filename) dataset["var"].dtype ```

Note that netCDF.default_fillvalues['i2'] is the value found at dataset["var"][3], which was never explicitly written. Here XArray seems to ignore the fill value.

Update

Okay, I think I understand why. In createVariable whether I use the default fill_value=None or set fill_value=False, XArray does not include _FillValue in dataset["var"].encoding. That, I think, is a bug. If you print(var) with fill_value=None, you'll see that NetCDF is setting the _FIllValue attribute. I don't think XArray should ignore it.

 
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