How to store encoded_nodata ?

[remi-braun]

I did an addition between two xarrays and as seen in the example I lost the attributes (except the CRS, I don't know if its normal)
I managed to set them back as stated, except the encoded_nodata:

# xda: xr.Dataarray
xda_out = xda + xda
xda_out.rio.write_crs(xda.rio.crs, inplace=True)   # OK
xda_out.rio.update_attrs(xda.rio.attrs, inplace=True)  # OK

# this line is not shown in the example, sets nodata = nan but forgets encoded_nodata
xda_out.rio.write_nodata(xda.rio.nodata, inplace=True) 

How do I achieve that ? Because I work with nodata pixels == nan and I need to write the correct value back when I save the raster to disk.

[remi-braun]

It works if I state this:

xda_out.encoding = xda.encoding

But isn't it a bit complicated to write 4 lines of code to get back the raster metadata integrity after a simple operation ?
Does a function doing all this exist ?

[snowman2]

http://xarray.pydata.org/en/stable/generated/xarray.set_options.html#xarray-set-options

You could try keep_attrs=True

[remi-braun]

Oh this could have been nice.
Unfortunately it doesn't keep nodata values 😢

I'll wrap these lines in a function then :)

[remi-braun]

Another question about this encoded_nodata value.
If I want to properly set the nodata on an array with the mask style, I must do:

    # xda: some xr.DataArray without set any nodata
    xda_nodata = xda.where(xda !=nodata_val)
    xda_nodata.rio.write_nodata(None, inplace=True)
    xda_nodata.encoding["_FillValue"] = nodata_val

Is there another shortcut ?

[snowman2]

Is there another shortcut ?

Not currently. Might not be bad to have a flag in write_nodata for when the nodata value is encoded.

xda_nodata.rio.write_nodata(nodata_val, encoded=True)

[remi-braun]

I was wondering if the function write_nodata should or not set the nodata pixels to np.nan in case encoded=True.
Right now I think this could be great, but there might be some downfall I don't see.

[snowman2]

See test in #314. It returns nan if rio.encoded_nodata is not None. So, no need to write it.

[remi-braun]

When do you plan to deliver your next release ? 😄

[snowman2]

Current plan is to wait until after xarray 0.18 is released due to the entrypoint addition (pydata/xarray#4697).