feat: add support for forcings in SimpleRunner

src/anemoi/inference/runners/simple.py

@@ -7,10 +7,14 @@
 # granted to it by virtue of its status as an intergovernmental organisation
 # nor does it submit to any jurisdiction.
 
-
 import logging
 from typing import Any
 
+import numpy as np
+
+from anemoi.inference.context import Context
+from anemoi.inference.types import Date
+from anemoi.inference.types import FloatArray
 from anemoi.inference.types import IntArray
 from anemoi.inference.types import State
 
@@ -58,11 +62,26 @@ def load_forcings_state(self, state: State, date: str) -> None:
         pass
 
 
+class UserProvidedForcings(Forcings):
+    trace_name = "user_provided"
+
+    def __init__(self, context: Context, forcings, variables: list[str], mask: IntArray):
+        super().__init__(context)
+        self.variables = variables
+        self.mask = mask
+        self.forcings = forcings
+
+    def load_forcings_array(self, dates: list[Date], current_state: State) -> FloatArray:
+        indices = [self.forcings["dates"].index(d) for d in dates]
+        result = np.stack([self.forcings["fields"][var][indices] for var in self.variables], axis=0)
+        return result.astype(np.float32)
+
+
 @runner_registry.register("simple")
 class SimpleRunner(Runner):
     """Use that runner when using the low level API."""
 
-    def __init__(self, *args: Any, **kwargs: Any) -> None:
+    def __init__(self, *args: Any, forcings: dict[str, Any] | None = None, **kwargs: Any) -> None:
         """Initialize the SimpleRunner.
 
         Parameters
@@ -73,6 +92,7 @@ def __init__(self, *args: Any, **kwargs: Any) -> None:
             Keyword arguments.
         """
         super().__init__(*args, **kwargs)
+        self.forcings = forcings
 
     def create_constant_computed_forcings(self, variables: list[str], mask: IntArray) -> list[Forcings]:
         """Create constant computed forcings.
@@ -151,5 +171,6 @@ def create_dynamic_coupled_forcings(self, variables: list[str], mask: IntArray)
         # This runner does not support coupled forcings
         # there are supposed to be already in the state dictionary
         # or managed by the user.
-        LOG.warning("Coupled forcings are not supported by this runner: %s", variables)
-        return []
+        # LOG.warning("Coupled forcings are not supported by this runner: %s", variables)
+
+        return [UserProvidedForcings(self, self.forcings, variables, mask)]