EWA Resampler hardcodes fill value to NaN

[djhoese]

A colleague tried to use EWA resampling on regular (non-dask) numpy arrays that were integers. She got errors about NaN not being able to be converted to an integer so she then specified the fill value with fill=0 and still got the same error. Turns out I have the fill value hardcoded to NaN:

https://github.com/pytroll/pyresample/blob/1f4c7fbe3985be068b4130fac7898f71eb7b5987/pyresample/ewa/ewa.py#L170-L171

This means integer data isn't actually handled. I need to create some tests for this to prove that there isn't some other reason I hardcoded this.

[djhoese]

Doesn't look like I'm doing this in the dask version of the EWA resampling code:

https://github.com/pytroll/pyresample/blob/1f4c7fbe3985be068b4130fac7898f71eb7b5987/pyresample/ewa/dask_ewa.py#L400-L410

[mraspaud]

Does it make sense to allow ewa on integer data? Because averaging is happening...

[djhoese]

Yes it has a maximum weight mode that is similar to nearest neighbor.