[ENH] Make transformers inherit TransformerMixin and add CollectionToSeriesWrapper

aeon/testing/testing_config.py

@@ -48,6 +48,8 @@
     ],
     # needs investigation
     "LeftSTAMPi": ["check_series_anomaly_detector_output"],
+    "SeriesToCollectionBroadcaster": ["check_transform_inverse_transform_equivalent"],
+    "CollectionToSeriesWrapper": ["check_transform_inverse_transform_equivalent"],
     # missed in legacy testing, changes state in predict/transform
     "FLUSSSegmenter": ["check_non_state_changing_method"],
     "ClaSPSegmenter": ["check_non_state_changing_method"],

aeon/transformations/base.py

@@ -7,11 +7,12 @@
 
 import numpy as np
 import pandas as pd
+from sklearn.base import TransformerMixin
 
 from aeon.base import BaseAeonEstimator
 
 
-class BaseTransformer(BaseAeonEstimator):
+class BaseTransformer(TransformerMixin, BaseAeonEstimator):
     """Transformer base class."""
 
     _tags = {
@@ -24,8 +25,6 @@ class BaseTransformer(BaseAeonEstimator):
 
     @abstractmethod
     def __init__(self):
-        self._estimator_type = "transformer"
-
         super().__init__()
 
     @abstractmethod

aeon/transformations/collection/__init__.py

@@ -1,8 +1,9 @@
 """Collection transformations."""
 
 __all__ = [
-    # base class and series wrapper
+    # base class and series broadcaster
     "BaseCollectionTransformer",
+    "SeriesToCollectionBroadcaster",
     # transformers
     "AutocorrelationFunctionTransformer",
     "ARCoefficientTransformer",
@@ -22,7 +23,6 @@
 
 from aeon.transformations.collection._acf import AutocorrelationFunctionTransformer
 from aeon.transformations.collection._ar_coefficient import ARCoefficientTransformer
-from aeon.transformations.collection._broadcaster import SeriesToCollectionBroadcaster
 from aeon.transformations.collection._downsample import DownsampleTransformer
 from aeon.transformations.collection._dwt import DWTTransformer
 from aeon.transformations.collection._hog1d import HOG1DTransformer
@@ -31,5 +31,8 @@
 from aeon.transformations.collection._periodogram import PeriodogramTransformer
 from aeon.transformations.collection._reduce import Tabularizer
 from aeon.transformations.collection._rescale import Centerer, MinMaxScaler, Normalizer
+from aeon.transformations.collection._series_broadcaster import (
+    SeriesToCollectionBroadcaster,
+)
 from aeon.transformations.collection._slope import SlopeTransformer
 from aeon.transformations.collection.base import BaseCollectionTransformer

aeon/transformations/collection/_broadcaster.py → aeon/transformations/collection/_series_broadcaster.py

@@ -38,22 +38,23 @@ class SeriesToCollectionBroadcaster(BaseCollectionTransformer):
         "input_data_type": "Collection",
         "output_data_type": "Collection",
         "capability:unequal_length": True,
+        "capability:inverse_transform": True,
         "X_inner_type": ["numpy3D", "np-list"],
     }
 
     def __init__(
         self,
         transformer: BaseSeriesTransformer,
     ) -> None:
-        # Setting tags before __init__() causes them to be overwritten. Hence we make
-        # a copy before init from the series transformer, then copy the tags of the
-        # BaseSeriesTransformer to this BaseCollectionTransformer
         self.transformer = transformer
+
+        super().__init__()
+
+        # Setting tags before __init__() causes them to be overwritten.
         tags_to_keep = SeriesToCollectionBroadcaster._tags
         tags_to_add = transformer.get_tags()
         for key in tags_to_keep:
             tags_to_add.pop(key, None)
-        super().__init__()
         self.set_tags(**tags_to_add)
 
     def _fit(self, X, y=None):
@@ -100,14 +101,14 @@ def _transform(self, X, y=None):
 
         """
         n_cases = get_n_cases(X)
-        """If fit is empty is true only single transform is used."""
         Xt = []
         if self.get_tag("fit_is_empty"):
             for i in range(n_cases):
                 Xt.append(self.transformer._transform(X[i]))
         else:
             for i in range(n_cases):
                 Xt.append(self.single_transformers_[i]._transform(X[i]))
+
         # Need to make it a valid collection
         for i in range(n_cases):
             if isinstance(Xt[i], np.ndarray) and Xt[i].ndim == 1:
@@ -134,14 +135,19 @@ def _inverse_transform(self, X, y=None):
             The transformed collection of time series, either a 3D numpy or a
             list of 2D numpy.
         """
-        n_cases = len(X)
+        n_cases = get_n_cases(X)
         Xt = []
         if self.get_tag("fit_is_empty"):
             for i in range(n_cases):
                 Xt.append(self.transformer._inverse_transform(X[i]))
         else:
             for i in range(n_cases):
                 Xt.append(self.single_transformers_[i]._inverse_transform(X[i]))
+
+        # Need to make it a valid collection
+        for i in range(n_cases):
+            if isinstance(Xt[i], np.ndarray) and Xt[i].ndim == 1:
+                Xt[i] = Xt[i].reshape(1, -1)
         return Xt
 
     @classmethod

aeon/transformations/collection/tests/test_broadcaster.py

@@ -1,7 +1,5 @@
 """Tests for SeriesToCollectionBroadcaster transformer."""
 
-__maintainer__ = ["baraline"]
-
 import pytest
 from numpy.testing import assert_array_almost_equal
 
@@ -14,7 +12,9 @@
     MockSeriesTransformerNoFit,
     MockUnivariateSeriesTransformer,
 )
-from aeon.transformations.collection._broadcaster import SeriesToCollectionBroadcaster
+from aeon.transformations.collection._series_broadcaster import (
+    SeriesToCollectionBroadcaster,
+)
 
 
 def test_broadcaster_tag_inheritance():
@@ -41,10 +41,9 @@ def test_broadcaster_tag_inheritance():
             assert post_constructor_tags[key] == mock_tags[key]
 
 
-df = [make_example_3d_numpy, make_example_3d_numpy_list]
-
-
-@pytest.mark.parametrize("data_gen", df)
+@pytest.mark.parametrize(
+    "data_gen", [make_example_3d_numpy, make_example_3d_numpy_list]
+)
 def test_broadcaster_methods_univariate(data_gen):
     """Test the broadcaster fit, transform and inverse transform method."""
     X, y = data_gen(n_channels=1)
@@ -64,7 +63,9 @@ def test_broadcaster_methods_univariate(data_gen):
         assert_array_almost_equal(X[i], X2[i])
 
 
-@pytest.mark.parametrize("data_gen", df)
+@pytest.mark.parametrize(
+    "data_gen", [make_example_3d_numpy, make_example_3d_numpy_list]
+)
 def test_broadcaster_methods_multivariate(data_gen):
     """Test the broadcaster fit, transform and inverse transform method."""
     X, y = data_gen(n_channels=3)

aeon/transformations/series/__init__.py

@@ -3,6 +3,7 @@
 __all__ = [
     "AutoCorrelationSeriesTransformer",
     "BaseSeriesTransformer",
+    "CollectionToSeriesWrapper",
     "ClaSPTransformer",
     "Dobin",
     "MatrixProfileTransformer",
@@ -27,6 +28,7 @@
 from aeon.transformations.series._bkfilter import BKFilter
 from aeon.transformations.series._boxcox import BoxCoxTransformer
 from aeon.transformations.series._clasp import ClaSPTransformer
+from aeon.transformations.series._collection_wrapper import CollectionToSeriesWrapper
 from aeon.transformations.series._diff import DifferenceTransformer
 from aeon.transformations.series._dobin import Dobin
 from aeon.transformations.series._log import LogTransformer

aeon/transformations/series/_collection_wrapper.py

@@ -0,0 +1,104 @@
+"""Class to wrap a collection transformer for single series."""
+
+__maintainer__ = ["MatthewMiddlehurst"]
+__all__ = ["CollectionToSeriesWrapper"]
+
+
+from aeon.transformations.collection.base import BaseCollectionTransformer
+from aeon.transformations.series.base import BaseSeriesTransformer
+
+
+class CollectionToSeriesWrapper(BaseSeriesTransformer):
+    """Wrap a ``BaseCollectionTransformer`` to run on single series datatypes.
+
+    Parameters
+    ----------
+    transformer : BaseCollectionTransformer
+        The collection transformer to wrap.
+
+    Examples
+    --------
+    >>> from aeon.transformations.series import CollectionToSeriesWrapper
+    >>> from aeon.transformations.collection.unequal_length import Resizer
+    >>> import numpy as np
+    >>> X = np.random.rand(1, 10)
+    >>> transformer = Resizer(resized_length=5)
+    >>> wrapper = CollectionToSeriesWrapper(transformer)
+    >>> X_t = wrapper.fit_transform(X)
+    """
+
+    # These tags are not set from the collection transformer.
+    _tags = {
+        "input_data_type": "Series",
+        "output_data_type": "Series",
+        "capability:inverse_transform": True,
+        "X_inner_type": "np.ndarray",
+    }
+
+    def __init__(
+        self,
+        transformer: BaseCollectionTransformer,
+    ) -> None:
+        self.transformer = transformer
+
+        super().__init__(axis=1)
+
+        # Setting tags before __init__() causes them to be overwritten.
+        tags_to_keep = CollectionToSeriesWrapper._tags
+        tags_to_add = transformer.get_tags()
+        for key in tags_to_keep:
+            tags_to_add.pop(key, None)
+        for key in ["capability:unequal_length", "removes_unequal_length"]:
+            tags_to_add.pop(key, None)
+        self.set_tags(**tags_to_add)
+
+    def _fit(self, X, y=None):
+        X = X.reshape(1, X.shape[0], X.shape[1])
+        self.collection_transformer_ = self.transformer.clone()
+        self.collection_transformer_.fit(X, y)
+
+    def _transform(self, X, y=None):
+        X = X.reshape(1, X.shape[0], X.shape[1])
+
+        t = self.transformer
+        if not self.get_tag("fit_is_empty"):
+            t = self.collection_transformer_
+
+        return t.transform(X, y)
+
+    def _fit_transform(self, X, y=None):
+        X = X.reshape(1, X.shape[0], X.shape[1])
+        self.collection_transformer_ = self.transformer.clone()
+        return self.collection_transformer_.fit_transform(X, y)
+
+    def _inverse_transform(self, X, y=None):
+        X = X.reshape(1, X.shape[0], X.shape[1])
+
+        t = self.transformer
+        if not self.get_tag("fit_is_empty"):
+            t = self.collection_transformer_
+
+        return t.inverse_transform(X, y)
+
+    @classmethod
+    def _get_test_params(cls, parameter_set="default"):
+        """Return testing parameter settings for the estimator.
+
+        Parameters
+        ----------
+        parameter_set : str, default="default"
+            Name of the set of test parameters to return, for use in tests. If no
+            special parameters are defined for a value, will return `"default"` set.
+
+        Returns
+        -------
+        params : dict or list of dict, default={}
+            Parameters to create testing instances of the class.
+            Each dict are parameters to construct an "interesting" test instance, i.e.,
+            `MyClass(**params)` or `MyClass(**params[i])` creates a valid test instance.
+        """
+        from aeon.testing.mock_estimators._mock_collection_transformers import (
+            MockCollectionTransformer,
+        )
+
+        return {"transformer": MockCollectionTransformer()}

aeon/transformations/series/tests/test_wrapper.py

@@ -0,0 +1,24 @@
+"""Tests for SeriesToCollectionBroadcaster transformer."""
+
+from aeon.testing.mock_estimators import MockCollectionTransformer
+from aeon.transformations.series import CollectionToSeriesWrapper
+
+
+def test_broadcaster_tag_inheritance():
+    """Test the ability to inherit tags from the BaseCollectionTransformer.
+
+    The broadcaster should always keep some tags related to single series
+    """
+    trans = MockCollectionTransformer()
+    class_tags = CollectionToSeriesWrapper._tags
+
+    bc = CollectionToSeriesWrapper(trans)
+
+    post_constructor_tags = bc.get_tags()
+    mock_tags = trans.get_tags()
+    # constructor_tags should match class_tags or, if not present, tags in transformer
+    for key in post_constructor_tags:
+        if key in class_tags:
+            assert post_constructor_tags[key] == class_tags[key]
+        elif key in mock_tags:
+            assert post_constructor_tags[key] == mock_tags[key]