Combine layers unstructured

[dbrakenhoff]

Allow combining layers in vertex datasets.

Add methods to check dataset or dataarray type:

• nlmod.grid.is_structured(ds)
• nlmod.grid.is_vertex(ds)
• nlmod.grid.is_layered(ds)

Added a GridTypeDims enum that specifies the dimensions for different grid types. Perhaps this and the above methods can be used across nlmod for consistency in how we check for different types of inputs. But that is best left to another PR if we agree this is the way to go.

[dbrakenhoff]

test fail related to codacy api outage: https://status.codacy.com/

[rubencalje]

Looks good. The use of Enum looks a bit complicated to me, but maybe you can show me what is the benefit of this at a later time.

[dbrakenhoff]

Looks good. The use of Enum looks a bit complicated to me, but maybe you can show me what is the benefit of this at a later time.

Good question. My reasoning so far: it's fancy, and it autocompletes nicely in your editor across files. It has a nice representation:

<GridTypeDims.STRUCTURED: ('y', 'x')>.

You can do a reverse lookup, like this:

nlmod.grid.GridTypeDims(da.dims) is nlmod.grid.GridTypeDims.STRUCTURED

Or even nicer:

class GridTypeDims(Enum):
    """Enum for grid dimensions."""

    STRUCTURED_LAYERED = ("layer", "y", "x")
    VERTEX_LAYERED = ("layer", "icell2d")
    STRUCTURED = ("y", "x")
    VERTEX = ("icell2d",)

    @classmethod
    def parse_dims(cls, ds):
        """Get GridTypeDim from dataset or dataarray.

        Parameters
        ----------
        ds : xr.Dataset or xr.DataArray
            Dataset or DataArray to parse.
        """
        for gridtype in GridTypeDims:
            if set(gridtype.value).issubset(ds.dims):
                return gridtype

Which allows

GridTypeDims.parse_dims(da) in (GridTypeDims.VERTEX, GridTypeDims.VERTEX_LAYERED)

or

GridTypeDims.parse_dims(da) is GridTypeDims.VERTEX_LAYERED)

[OnnoEbbens]

Nice improvement! I also didn't know about the enum inheritance but it looks nice. I think we should implement this for all the gridtype checks. We can maybe even remove the gridtype attribute.

Especially looking forward to replace this code in the resample module for a decent gridtype check:
if len(da.shape) > 1 and len(da.y) == da.shape[-2] and len(da.x) == da.shape[-1]