make mapper a property of fields

heracles/fields.py

@@ -83,9 +83,15 @@ def __init_subclass__(cls, *, spin: int | None = None) -> None:
                 break
         cls.__ncol = (ncol - nopt, ncol)
 
-    def __init__(self, *columns: str, mask: str | None = None) -> None:
+    def __init__(
+        self,
+        mapper: Mapper | None,
+        *columns: str,
+        mask: str | None = None,
+    ) -> None:
         """Initialise the field."""
         super().__init__()
+        self.__mapper = mapper
         self.__columns = self._init_columns(*columns) if columns else None
         self.__mask = mask
 
@@ -110,6 +116,20 @@ def _init_columns(cls, *columns: str) -> Columns:
             raise ValueError(msg)
         return columns + (None,) * (nmax - len(columns))
 
+    @property
+    def mapper(self) -> Mapper | None:
+        """Return the mapper used by this field."""
+        return self.__mapper
+
+    @property
+    def mapper_or_error(self) -> Mapper:
+        """Return the mapper used by this field, or raise a :class:`ValueError`
+        if not set."""
+        if self.__mapper is None:
+            msg = "no mapper for field"
+            raise ValueError(msg)
+        return self.__mapper
+
     @property
     def columns(self) -> Columns | None:
         """Return the catalogue columns used by this field."""
@@ -143,7 +163,6 @@ def mask(self) -> str | None:
     async def __call__(
         self,
         catalog: Catalog,
-        mapper: Mapper,
         *,
         progress: ProgressTask | None = None,
     ) -> ArrayLike:
@@ -211,12 +230,14 @@ def nbar(self, nbar: float | None) -> None:
     async def __call__(
         self,
         catalog: Catalog,
-        mapper: Mapper,
         *,
         progress: ProgressTask | None = None,
     ) -> ArrayLike:
         """Map the given catalogue."""
 
+        # get mapper
+        mapper = self.mapper_or_error
+
         # get catalogue column definition
         col = self.columns_or_error
 
@@ -297,12 +318,14 @@ class ScalarField(Field, spin=0):
     async def __call__(
         self,
         catalog: Catalog,
-        mapper: Mapper,
         *,
         progress: ProgressTask | None = None,
     ) -> ArrayLike:
         """Map real values from catalogue to HEALPix map."""
 
+        # get mapper
+        mapper = self.mapper_or_error
+
         # get the column definition of the catalogue
         *col, wcol = self.columns_or_error
 
@@ -375,12 +398,14 @@ class ComplexField(Field, spin=0):
     async def __call__(
         self,
         catalog: Catalog,
-        mapper: Mapper,
         *,
         progress: ProgressTask | None = None,
     ) -> ArrayLike:
         """Map complex values from catalogue to HEALPix map."""
 
+        # get mapper
+        mapper = self.mapper_or_error
+
         # get the column definition of the catalogue
         *col, wcol = self.columns_or_error
 
@@ -446,12 +471,14 @@ class Visibility(Field, spin=0):
     async def __call__(
         self,
         catalog: Catalog,
-        mapper: Mapper,
         *,
         progress: ProgressTask | None = None,
     ) -> ArrayLike:
         """Create a visibility map from the given catalogue."""
 
+        # get mapper
+        mapper = self.mapper_or_error
+
         # make sure that catalogue has a visibility map
         vmap = catalog.visibility
         if vmap is None:
@@ -487,12 +514,14 @@ class Weights(Field, spin=0):
     async def __call__(
         self,
         catalog: Catalog,
-        mapper: Mapper,
         *,
         progress: ProgressTask | None = None,
     ) -> ArrayLike:
         """Map catalogue weights."""
 
+        # get mapper
+        mapper = self.mapper_or_error
+
         # get the columns for this field
         *col, wcol = self.columns_or_error
 

heracles/maps/_mapping.py

@@ -38,14 +38,11 @@
     from heracles.fields import Field
     from heracles.progress import Progress, ProgressTask
 
-    from ._mapper import Mapper
-
 
 async def _map_progress(
     key: tuple[Any, ...],
     field: Field,
     catalog: Catalog,
-    mapper: Mapper,
     progress: Progress | None,
 ) -> NDArray:
     """
@@ -59,7 +56,7 @@ async def _map_progress(
     else:
         task = None
 
-    result = await field(catalog, mapper, progress=task)
+    result = await field(catalog, progress=task)
 
     if progress is not None:
         task.remove()
@@ -69,7 +66,6 @@ async def _map_progress(
 
 
 def map_catalogs(
-    mapper: Mapper,
     fields: Mapping[Any, Field],
     catalogs: Mapping[Any, Catalog],
     *,
@@ -116,7 +112,7 @@ def map_catalogs(
             for key, field, catalog in items:
                 if toc_match(key, include, exclude):
                     keys.append(key)
-                    coros.append(_map_progress(key, field, catalog, mapper, prog))
+                    coros.append(_map_progress(key, field, catalog, prog))
 
             # run all coroutines concurrently
             try:
@@ -141,7 +137,7 @@ def map_catalogs(
 
 
 def transform_maps(
-    mapper: Mapper,
+    fields: Mapping[Any, Field],
     maps: Mapping[tuple[Any, Any], NDArray],
     *,
     out: MutableMapping[tuple[Any, Any], NDArray] | None = None,
@@ -175,7 +171,13 @@ def transform_maps(
                     total=None,
                 )
 
-            alms = mapper.transform(m)
+            try:
+                field = fields[k]
+            except KeyError:
+                msg = f"unknown field name: {k}"
+                raise ValueError(msg)
+
+            alms = field.mapper_or_error.transform(m)
 
             if isinstance(alms, tuple):
                 out[f"{k}_E", i] = alms[0]