Record cell characteristics from aggregation cell conditions

[davidhassell]

Since 3.15.2, the cells keyword of cf.aggregate allows fields to be aggregated sperately according to the characteristics of their dimension coordinates - namely cell spacing and cell size.

It would be useful to automatically record these characteristics on the aggregated fields, so that it is easy to see afterwards which conditions were passed.

Since the characteristics apply to dimension coordinate constructs only, they should be recorded on those constructs.

I propose four new DimensionCoordinate methods of [del|get|has|set]_cell_characterstics to allow the cell characteristics to be stored and subsequently accessed.

[bnlawrence]

Would we have a controlled vocabulary of possible characteristics?

[davidhassell]

Would we have a controlled vocabulary of possible characteristics?

No - that would be up to a user application (such as cfstore) to map from a saved numerical-like characteristic of (say) {'cellsize': <CF Query: (wi [28, 31] day)>} to something that that application likes.

other examples of stored characteristics that apply to CANARI

  {'cellsize': <CF Query: (isclose 1 hour)>}

  {'cellsize': <CF Query: (isclose 0 hour)>,
   'spacing': <CF Query: (isclose 1 hour)>}

  {'cellsize': <CF Query: (isclose 3 hour)>}

  {'cellsize': <CF Query: (isclose 0 hour)>,
   'spacing': <CF Query: (isclose 3 hour)>}

  {'cellsize': <CF Query: (isclose 6 hour)>}

  {'cellsize': <CF Query: (isclose 0 hour)>,
   'spacing': <CF Query: (isclose 6 hour)>}

  {'cellsize': <CF Query: (isclose 1 day)>}

E.g.

if cf.wi(28, 31, 'd').equals(cellsize):
    cellsize = "1 month"

if cf.isclose(0, 'h').equals(cellsize) and cf.isclose(3, 'h').equals(spacing):
    cellsize = "0 hour"
    spacing = "3 hour"

It's possible to be more general if you know all characteristics are cf.Query objects (which you will know):

if char.operator in ('isclose', 'eq'):
    x = char.value
    char = f"{x.datum()} {x.Units.formatted(names=True)}"
elif cf.wi(28, 31, 'd').equals(char):
    char = "1 month"
elif cf.wi(360, 366, 'd').equals(char):
    char = "1 year"