Adapter scale and shift

bayesflow/adapters/adapter.py

@@ -555,6 +555,24 @@ def rename(self, from_key: str, to_key: str):
         self.transforms.append(Rename(from_key, to_key))
         return self
 
+    def scale(self, keys: str | Sequence[str], by: float | np.ndarray):
+        from .transforms import Scale
+
+        if isinstance(keys, str):
+            keys = [keys]
+
+        self.transforms.append(MapTransform({key: Scale(scale=by) for key in keys}))
+        return self
+
+    def shift(self, keys: str | Sequence[str], by: float | np.ndarray):
+        from .transforms import Shift
+
+        if isinstance(keys, str):
+            keys = [keys]
+
+        self.transforms.append(MapTransform({key: Shift(shift=by) for key in keys}))
+        return self
+
     def sqrt(self, keys: str | Sequence[str]):
         """Append an :py:class:`~transforms.Sqrt` transform to the adapter.
 

bayesflow/adapters/transforms/__init__.py

@@ -14,6 +14,8 @@
 from .numpy_transform import NumpyTransform
 from .one_hot import OneHot
 from .rename import Rename
+from .scale import Scale
+from .shift import Shift
 from .sqrt import Sqrt
 from .standardize import Standardize
 from .to_array import ToArray

bayesflow/adapters/transforms/scale.py

@@ -0,0 +1,27 @@
+from keras.saving import (
+    deserialize_keras_object as deserialize,
+    register_keras_serializable as serializable,
+    serialize_keras_object as serialize,
+)
+import numpy as np
+
+from .elementwise_transform import ElementwiseTransform
+
+
+@serializable(package="bayesflow.adapters")
+class Scale(ElementwiseTransform):
+    def __init__(self, scale: np.typing.ArrayLike):
+        self.scale = np.array(scale)
+
+    @classmethod
+    def from_config(cls, config: dict, custom_objects=None) -> "ElementwiseTransform":
+        return cls(scale=deserialize(config["scale"]))
+
+    def get_config(self) -> dict:
+        return {"scale": serialize(self.scale)}
+
+    def forward(self, data: np.ndarray, **kwargs) -> np.ndarray:
+        return data * self.scale
+
+    def inverse(self, data: np.ndarray, **kwargs) -> np.ndarray:
+        return data / self.scale

bayesflow/adapters/transforms/shift.py

@@ -0,0 +1,27 @@
+from keras.saving import (
+    deserialize_keras_object as deserialize,
+    register_keras_serializable as serializable,
+    serialize_keras_object as serialize,
+)
+import numpy as np
+
+from .elementwise_transform import ElementwiseTransform
+
+
+@serializable(package="bayesflow.adapters")
+class Shift(ElementwiseTransform):
+    def __init__(self, shift: np.typing.ArrayLike):
+        self.shift = np.array(shift)
+
+    @classmethod
+    def from_config(cls, config: dict, custom_objects=None) -> "ElementwiseTransform":
+        return cls(shift=deserialize(config["shift"]))
+
+    def get_config(self) -> dict:
+        return {"shift": serialize(self.shift)}
+
+    def forward(self, data: np.ndarray, **kwargs) -> np.ndarray:
+        return data + self.shift
+
+    def inverse(self, data: np.ndarray, **kwargs) -> np.ndarray:
+        return data - self.shift

tests/test_adapters/conftest.py

@@ -20,6 +20,8 @@ def adapter():
         .constrain("p2", lower=0)
         .apply(include="p2", forward="exp", inverse="log")
         .apply(include="p2", forward="log1p")
+        .scale("x", by=[-1, 2])
+        .shift("x", by=2)
         .standardize(exclude=["t1", "t2", "o1"])
         .drop("d1")
         .one_hot("o1", 10)

tests/test_adapters/test_adapters.py

@@ -97,16 +97,16 @@ def test_simple_transforms(random_data):
 
     result = ad(random_data)
 
-    assert np.array_equal(result["p2"], np.log(random_data["p2"]))
-    assert np.array_equal(result["t2"], np.log(random_data["t2"]))
-    assert np.array_equal(result["t1"], np.log1p(random_data["t1"]))
-    assert np.array_equal(result["p1"], np.sqrt(random_data["p1"]))
+    assert np.allclose(result["p2"], np.log(random_data["p2"]))
+    assert np.allclose(result["t2"], np.log(random_data["t2"]))
+    assert np.allclose(result["t1"], np.log1p(random_data["t1"]))
+    assert np.allclose(result["p1"], np.sqrt(random_data["p1"]))
 
     # inverse results should match the original input
     inverse = ad(result, inverse=True)
 
-    assert np.array_equal(inverse["p2"], random_data["p2"])
-    assert np.array_equal(inverse["t2"], random_data["t2"])
-    assert np.array_equal(inverse["t1"], random_data["t1"])
-    # numerical inaccuries prevent np.array_equal to work here
+    assert np.allclose(inverse["p2"], random_data["p2"])
+    assert np.allclose(inverse["t2"], random_data["t2"])
+    assert np.allclose(inverse["t1"], random_data["t1"])
+
     assert np.allclose(inverse["p1"], random_data["p1"])