[FSTORE-1412][Append] Add std_dev alias for transformation functions (#1011)

Author: javierdlrm

python/hsfs/core/feature_descriptive_statistics.py

@@ -86,7 +86,9 @@ def __init__(
         self._max = max
         self._sum = sum
         self._mean = mean
-        self._std_dev = std_dev
+        # Accept the legacy lowercase ``stddev`` key (e.g. from backend payloads
+        # or older callers) so the rename to ``std_dev`` stays backward compatible.
+        self._std_dev = std_dev if std_dev is not None else kwargs.get("stddev")
         self._percentiles = percentiles
         self._distinctness = distinctness
         self._entropy = entropy

python/hsfs/transformation_statistics.py

@@ -21,7 +21,7 @@
 from typing import TYPE_CHECKING, Any
 
 import humps
-from hopsworks_apigen import public
+from hopsworks_apigen import deprecated, public
 
 
 if TYPE_CHECKING:
@@ -65,7 +65,9 @@ def __init__(
         self._max = max
         self._sum = sum
         self._mean = mean
-        self._std_dev = std_dev
+        # Accept the legacy lowercase ``stddev`` key (e.g. from backend payloads
+        # or older callers) so the rename to ``std_dev`` stays backward compatible.
+        self._std_dev = std_dev if std_dev is not None else kwargs.get("stddev")
         self._percentiles = percentiles
         self._distinctness = distinctness
         self._entropy = entropy
@@ -157,6 +159,18 @@ def std_dev(self) -> float | None:
         """Standard deviation of the feature values."""
         return self._std_dev
 
+    @public
+    @property
+    @deprecated(
+        "hsfs.transformation_statistics.FeatureTransformationStatistics.std_dev"
+    )
+    def stddev(self) -> float | None:
+        """Standard deviation of the feature values.
+
+        Deprecated alias for [`std_dev`][hsfs.transformation_statistics.FeatureTransformationStatistics.std_dev].
+        """
+        return self._std_dev
+
     @public
     @property
     def percentiles(self) -> Mapping[str, float] | None: