Load no-time vars as numpy arrays in to_windowed_arrays

src/parcels/_core/_windowed_array.py

@@ -108,4 +108,6 @@ def maybe_windowed(data: xr.DataArray, max_levels: int | None = None):
         return data
     if data.dims and data.dims[0] == "time" and is_dask_collection(data.data):
         return WindowedArray(data, max_levels=max_levels)
+    elif data.dims and data.dims[0] == "mockT" and is_dask_collection(data.data):
+        return data.compute()
     return data

src/parcels/_core/model.py

@@ -7,6 +7,7 @@
 import cf_xarray  # noqa: F401
 import uxarray as ux
 import xarray as xr
+from dask import is_dask_collection
 
 import parcels._sgrid as sgrid
 import parcels._typing as ptyping
@@ -102,6 +103,12 @@ def to_windowed_arrays(self, *, max_levels: int | None = None) -> Self:
             and ``max_levels`` then bounds its size.
         """
         windowed = self.__dict__.setdefault("_windowed", {})
+        for dim in ["lon", "lat"]:
+            # ensure lon and lat are loaded into memory for dask-backed datasets
+            if is_dask_collection(self.data[dim]):
+                self.data[dim].load()
+        if "depth" in self.data.dims and is_dask_collection(self.data["depth"]):
+            self.data["depth"].load()
         for name in self.scalar_field_names:
             current = windowed.get(name, self.data[name])
             windowed[name] = maybe_windowed(current, max_levels=max_levels)

src/parcels/_reprs.py

@@ -8,7 +8,10 @@
 
 import numpy as np
 import xarray as xr
+import zarr
+from dask.base import is_dask_collection
 
+from parcels._core._windowed_array import WindowedArray
 from parcels._python import isinstance_noimport
 
 if TYPE_CHECKING:
@@ -190,13 +193,15 @@ class _FieldSetDescriptionRow:
     model_id: int | None
     name: str
     interp_method_or_value: str
+    backend: str | None = None
 
     def to_dict(self) -> dict[str, str]:
         return {
             "Name": self.name,
             "Type": self.type_,
             "Grid number": str(self.model_id) if self.model_id is not None else "-",
             "Interp method / value": self.interp_method_or_value,
+            "Parcels backend": self.backend if self.backend is not None else "-",
         }
 
 
@@ -213,6 +218,22 @@ def _print_time_interval(time_interval: TimeInterval | None) -> str:
     return repr((time_interval.left, time_interval.right))
 
 
+def _field_backend(field: Field | VectorField) -> str | None:
+    if hasattr(field, "data"):
+        if isinstance(field.data, WindowedArray):
+            return "WindowedArray"
+        elif is_dask_collection(field.data.data):
+            return "Dask"
+        elif isinstance(field.data.variable._data, zarr.Array):
+            return "Zarr"
+        elif isinstance(field.data.data, np.ndarray):
+            return "NumPy"
+        else:
+            return type(field.data).__name__
+    else:
+        return None
+
+
 def fieldset_describe(fieldset: FieldSet) -> str:
     rows: list[_FieldSetDescriptionRow] = []
     models: dict[int, int] = {}  # mapping of memory ID to a human readable ID
@@ -235,6 +256,7 @@ def fieldset_describe(fieldset: FieldSet) -> str:
                 model_id=model_id,
                 name=field.name,
                 interp_method_or_value=repr(field.interp_method),
+                backend=_field_backend(field),
             )
         )
     for k, v in fieldset.context.items():
@@ -244,6 +266,7 @@ def fieldset_describe(fieldset: FieldSet) -> str:
                 model_id=None,
                 name=k,
                 interp_method_or_value=repr(v),
+                backend=None,
             )
         )
     return (

tests/test_fieldset.py

@@ -7,7 +7,8 @@
 import pandas as pd
 import pytest
 
-from parcels import Field, ParticleFile, ParticleSet, XGrid, convert
+import parcels.tutorial
+from parcels import Field, ParticleFile, ParticleSet, XGrid, convert, open_raw_zarr
 from parcels._core.fieldset import FieldSet, _datetime_to_msg
 from parcels._core.model import _default_vector_field_components
 from parcels._datasets.structured.generic import datasets as datasets_structured
@@ -398,21 +399,94 @@ def test_fieldset_describe(fieldset_two_models: FieldSet):
     fieldset = fieldset_two_models
     io = StringIO()
     expected = """\
-| Name           | Type        | Grid number   | Interp method / value   |
-|:---------------|:------------|:--------------|:------------------------|
-| my_list        | Context     | -             | [1, 2, 'hello']         |
-| my_value       | Context     | -             | 2.0                     |
-| U              | Field       | 0             | XLinear(...)            |
-| V              | Field       | 0             | XLinear(...)            |
-| UV             | VectorField | 0             | XLinear_Velocity(...)   |
-| U_wind         | Field       | 1             | XLinear(...)            |
-| V_wind         | Field       | 1             | XLinear(...)            |
-| UV_wind        | VectorField | 1             | XLinear_Velocity(...)   |
-| constant_field | Field       | 2             | XConstantField(...)     |
+| Name           | Type        | Grid number   | Interp method / value   | Backend   |
+| Name           | Type        | Grid number   | Interp method / value   | Parcels backend   |
+|:---------------|:------------|:--------------|:------------------------|:------------------|
+| my_list        | Context     | -             | [1, 2, 'hello']         | -                 |
+| my_value       | Context     | -             | 2.0                     | -                 |
+| U              | Field       | 0             | XLinear(...)            | NumPy             |
+| V              | Field       | 0             | XLinear(...)            | NumPy             |
+| UV             | VectorField | 0             | XLinear_Velocity(...)   | -                 |
+| U_wind         | Field       | 1             | XLinear(...)            | NumPy             |
+| V_wind         | Field       | 1             | XLinear(...)            | NumPy             |
+| UV_wind        | VectorField | 1             | XLinear_Velocity(...)   | -                 |
+| constant_field | Field       | 2             | XConstantField(...)     | NumPy             |
 
 mesh: flat
 time interval: (np.datetime64('2000-01-01T00:00:00.000000000'), np.datetime64('2001-01-01T00:00:00.000000000'))
 """
     fieldset.describe(io)
     actual = io.getvalue()
     assert actual == expected
+
+
+def test_fieldset_describe_backends(tmp_path):
+    ds_u = parcels.tutorial.open_dataset("NemoNorthSeaORCA025-N006_data/U")
+    ds_v = parcels.tutorial.open_dataset("NemoNorthSeaORCA025-N006_data/V")
+    ds_w = parcels.tutorial.open_dataset("NemoNorthSeaORCA025-N006_data/W")
+    ds_coords = parcels.tutorial.open_dataset("NemoNorthSeaORCA025-N006_data/mesh_mask")[["glamf", "gphif"]]
+
+    ds_fset = convert.nemo_to_sgrid(
+        fields={"U": ds_u["uo"], "V": ds_v["vo"], "W": ds_w["wo"]},
+        coords=ds_coords,
+    )
+    fieldset = FieldSet.from_sgrid_conventions(ds_fset)
+
+    io = StringIO()
+    expected = """\
+| Name   | Type        |   Grid number | Interp method / value   | Parcels backend   |
+|:-------|:------------|--------------:|:------------------------|:------------------|
+| U      | Field       |             0 | XLinear(...)            | Dask              |
+| V      | Field       |             0 | XLinear(...)            | Dask              |
+| W      | Field       |             0 | XLinear(...)            | Dask              |
+| UV     | VectorField |             0 | CGrid_Velocity(...)     | -                 |
+| UVW    | VectorField |             0 | CGrid_Velocity(...)     | -                 |
+
+mesh: spherical
+time interval: (np.datetime64('2000-01-02T12:00:00.000000000'), np.datetime64('2000-01-12T12:00:00.000000000'))
+"""
+    fieldset.describe(io)
+    actual = io.getvalue()
+    assert actual == expected
+
+    # Also run with WindowedArray backend
+    fieldset = fieldset.to_windowed_arrays()
+
+    io = StringIO()
+    expected = """\
+| Name   | Type        |   Grid number | Interp method / value   | Parcels backend   |
+|:-------|:------------|--------------:|:------------------------|:------------------|
+| U      | Field       |             0 | XLinear(...)            | WindowedArray     |
+| V      | Field       |             0 | XLinear(...)            | WindowedArray     |
+| W      | Field       |             0 | XLinear(...)            | WindowedArray     |
+| UV     | VectorField |             0 | CGrid_Velocity(...)     | -                 |
+| UVW    | VectorField |             0 | CGrid_Velocity(...)     | -                 |
+
+mesh: spherical
+time interval: (np.datetime64('2000-01-02T12:00:00.000000000'), np.datetime64('2000-01-12T12:00:00.000000000'))
+"""
+    fieldset.describe(io)
+    actual = io.getvalue()
+    assert actual == expected
+
+    path = tmp_path / "ds.zarr"
+    ds_fset.to_zarr(path)
+    ds_zarr = open_raw_zarr(path)
+    fieldset = FieldSet.from_sgrid_conventions(ds_zarr)
+
+    io = StringIO()
+    expected = """\
+| Name   | Type        |   Grid number | Interp method / value   | Parcels backend   |
+|:-------|:------------|--------------:|:------------------------|:------------------|
+| U      | Field       |             0 | XLinear(...)            | Zarr              |
+| V      | Field       |             0 | XLinear(...)            | Zarr              |
+| W      | Field       |             0 | XLinear(...)            | Zarr              |
+| UV     | VectorField |             0 | CGrid_Velocity(...)     | -                 |
+| UVW    | VectorField |             0 | CGrid_Velocity(...)     | -                 |
+
+mesh: spherical
+time interval: (np.datetime64('2000-01-02T12:00:00.000000000'), np.datetime64('2000-01-12T12:00:00.000000000'))
+"""
+    fieldset.describe(io)
+    actual = io.getvalue()
+    assert actual == expected