utils.mask_missing_data - What is the definition of a missing value?

[Michael Anderson <mi...@gmail.com>]

I'm working on https://issues.apache.org/jira/browse/CLIMATE-797.

The comments in the method in question state:

If any of dataset in dataset_array has missing values at a grid point,
the values at the grid point in all other datasets are masked.


The problem here is that the method assumes a masked array is passed
as an input.

If a regular numpy array (e.g. OCW dataset) is passed, it does not
have a mask attribute and an error is thrown


1.  I could tidy up the error handling to make it more clear to the
caller that a masked array was expected.


2.  I could check if a mask exists and use that.  In the case of the
mask not being supplied, I could carry out the intent of the function
and manually check the array for "missing values".  Other than None or
NaN, are there any other values that by convention constitute missing?
 The netCDF default fill values?


Preferences on the approach and / or suggestions on the second approach?


Thanks,


Michael A. Anderson