Concise way to filter data in xarray

Question

I need to apply a very simple \'match statement\' to the values in an xarray array:

1. Where the value > 0, make 2
2. Where the value == 0, make 0
3. Wher

Answer 1

xarray now supports .where(condition, other), so this is now valid:

result = date_by_items.where(date_by_items > 0, 2)

Answer 2

If you are happy to load your data in-memory as a NumPy array, you can modify the DataArray values in place with NumPy:

date_by_items.values[date_by_items.values > 0] = 2

The cleanest way to handle this would be if xarray supported the other argument to where, but we haven't implemented that yet (hopefully soon -- the groundwork has been laid!). When that works, you'll be able to write date_by_items.where(date_by_items > 0, 2).

Either way, you'll need to do this twice to apply both your criteria.