issue_comments: 248170532

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https://github.com/pydata/xarray/issues/1008#issuecomment-248170532 https://api.github.com/repos/pydata/xarray/issues/1008 248170532 MDEyOklzc3VlQ29tbWVudDI0ODE3MDUzMg== 12339722 2016-09-20T00:44:27Z 2016-09-20T00:44:27Z NONE

Thanks for your reply.

Variables dbz, vr and sw have the _FillValue attribute, whose value is equal to _FillValue: -999.0

<type 'netCDF4._netCDF4.Variable'> float32 dbz(z, y, x) _FillValue: -999.0 units: dBZ long_name: reflectivity in log units unlimited dimensions: current shape = (9, 461, 461) filling on

It seems that xarray will convert the dtype from float32 to float64, while the variable in netCDF4 file has the attribute _FillValue, xr.open_dataset auto identify the _FillValue in the variable and mask it with np.nan , however the variable is also changed into float64. I think this result with default argument is not reasonable enough, as this type conversion is not necessary in fact.

Using mask_and_scale=False will maintain the variable in float32 and retain the _FillValue attribute of variable. However, what i want is mask but maintain the dtype in float32. Is it has possible bug in the internal of the open_dataset method ?

 
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