take docstrings outside imputer base class

feature_engine/_docstrings/fit_attributes.py

@@ -15,3 +15,7 @@
 _binner_dict_docstring = """binner_dict_:
          Dictionary with the interval limits per variable.
      """.rstrip()
+
+_imputer_dict_docstring = """imputer_dict_:
+        Dictionary with the values to replace missing data in each variable.
+    """.rstrip()

feature_engine/_docstrings/methods.py

@@ -40,3 +40,8 @@
 _transform_discretiser_docstring = """transform:
         Sort continuous variable values into the intervals.
     """.rstrip()
+
+# used in imputation module
+_transform_imputers_docstring = """transform:
+        Impute missing data.
+    """.rstrip()

feature_engine/imputation/arbitrary_number.py

@@ -10,12 +10,14 @@
 )
 from feature_engine._docstrings.fit_attributes import (
     _feature_names_in_docstring,
+    _imputer_dict_docstring,
     _n_features_in_docstring,
     _variables_attribute_docstring,
 )
 from feature_engine._docstrings.methods import (
     _fit_not_learn_docstring,
     _fit_transform_docstring,
+    _transform_imputers_docstring,
 )
 from feature_engine._docstrings.substitute import Substitution
 from feature_engine._variable_handling.init_parameter_checks import (
@@ -29,12 +31,12 @@
 
 
 @Substitution(
-    imputer_dict_=BaseImputer._imputer_dict_docstring,
+    imputer_dict_=_imputer_dict_docstring,
     variables_=_variables_attribute_docstring,
     feature_names_in_=_feature_names_in_docstring,
     n_features_in_=_n_features_in_docstring,
     fit=_fit_not_learn_docstring,
-    transform=BaseImputer._transform_docstring,
+    transform=_transform_imputers_docstring,
     fit_transform=_fit_transform_docstring,
 )
 class ArbitraryNumberImputer(BaseImputer):

feature_engine/imputation/base_imputer.py

@@ -2,27 +2,14 @@
 from sklearn.base import BaseEstimator, TransformerMixin
 from sklearn.utils.validation import check_is_fitted
 
-from feature_engine.dataframe_checks import _check_X_matches_training_df, check_X
 from feature_engine._base_transformers.mixins import GetFeatureNamesOutMixin
+from feature_engine.dataframe_checks import _check_X_matches_training_df, check_X
 from feature_engine.tags import _return_tags
 
 
 class BaseImputer(BaseEstimator, TransformerMixin, GetFeatureNamesOutMixin):
     """shared set-up checks and methods across imputers"""
 
-    _variables_numerical_docstring = """variables: list, default=None
-        The list of variables to impute. If None, the imputer will select
-        all numerical variables.
-        """.rstrip()
-
-    _imputer_dict_docstring = """imputer_dict_:
-        Dictionary with the values to replace missing data in each variable.
-        """.rstrip()
-
-    _transform_docstring = """transform:
-        Impute missing data.
-        """.rstrip()
-
     def _transform(self, X: pd.DataFrame) -> pd.DataFrame:
         """
         Common checks before transforming data:

feature_engine/imputation/categorical.py

@@ -7,10 +7,14 @@
 
 from feature_engine._docstrings.fit_attributes import (
     _feature_names_in_docstring,
+    _imputer_dict_docstring,
     _n_features_in_docstring,
     _variables_attribute_docstring,
 )
-from feature_engine._docstrings.methods import _fit_transform_docstring
+from feature_engine._docstrings.methods import (
+    _fit_transform_docstring,
+    _transform_imputers_docstring,
+)
 from feature_engine._docstrings.substitute import Substitution
 from feature_engine._variable_handling.init_parameter_checks import (
     _check_init_parameter_variables,
@@ -25,11 +29,11 @@
 
 
 @Substitution(
-    imputer_dict_=BaseImputer._imputer_dict_docstring,
+    imputer_dict_=_imputer_dict_docstring,
     variables_=_variables_attribute_docstring,
     feature_names_in_=_feature_names_in_docstring,
     n_features_in_=_n_features_in_docstring,
-    transform=BaseImputer._transform_docstring,
+    transform=_transform_imputers_docstring,
     fit_transform=_fit_transform_docstring,
 )
 class CategoricalImputer(BaseImputer):

feature_engine/imputation/end_tail.py

@@ -7,10 +7,17 @@
 
 from feature_engine._docstrings.fit_attributes import (
     _feature_names_in_docstring,
+    _imputer_dict_docstring,
     _n_features_in_docstring,
     _variables_attribute_docstring,
 )
-from feature_engine._docstrings.methods import _fit_transform_docstring
+from feature_engine._docstrings.init_parameters.all_trasnformers import (
+    _variables_numerical_docstring,
+)
+from feature_engine._docstrings.methods import (
+    _fit_transform_docstring,
+    _transform_imputers_docstring,
+)
 from feature_engine._docstrings.substitute import Substitution
 from feature_engine._variable_handling.init_parameter_checks import (
     _check_init_parameter_variables,
@@ -23,12 +30,12 @@
 
 
 @Substitution(
-    variables=BaseImputer._variables_numerical_docstring,
-    imputer_dict_=BaseImputer._imputer_dict_docstring,
+    variables=_variables_numerical_docstring,
+    imputer_dict_=_imputer_dict_docstring,
     variables_=_variables_attribute_docstring,
     feature_names_in_=_feature_names_in_docstring,
     n_features_in_=_n_features_in_docstring,
-    transform=BaseImputer._transform_docstring,
+    transform=_transform_imputers_docstring,
     fit_transform=_fit_transform_docstring,
 )
 class EndTailImputer(BaseImputer):

feature_engine/imputation/mean_median.py

@@ -7,10 +7,17 @@
 
 from feature_engine._docstrings.fit_attributes import (
     _feature_names_in_docstring,
+    _imputer_dict_docstring,
     _n_features_in_docstring,
     _variables_attribute_docstring,
 )
-from feature_engine._docstrings.methods import _fit_transform_docstring
+from feature_engine._docstrings.init_parameters.all_trasnformers import (
+    _variables_numerical_docstring,
+)
+from feature_engine._docstrings.methods import (
+    _fit_transform_docstring,
+    _transform_imputers_docstring,
+)
 from feature_engine._docstrings.substitute import Substitution
 from feature_engine._variable_handling.init_parameter_checks import (
     _check_init_parameter_variables,
@@ -23,12 +30,12 @@
 
 
 @Substitution(
-    variables=BaseImputer._variables_numerical_docstring,
-    imputer_dict_=BaseImputer._imputer_dict_docstring,
+    variables=_variables_numerical_docstring,
+    imputer_dict_=_imputer_dict_docstring,
     variables_=_variables_attribute_docstring,
     feature_names_in_=_feature_names_in_docstring,
     n_features_in_=_n_features_in_docstring,
-    transform=BaseImputer._transform_docstring,
+    transform=_transform_imputers_docstring,
     fit_transform=_fit_transform_docstring,
 )
 class MeanMedianImputer(BaseImputer):

feature_engine/imputation/random_sample.py

@@ -11,7 +11,10 @@
     _n_features_in_docstring,
     _variables_attribute_docstring,
 )
-from feature_engine._docstrings.methods import _fit_transform_docstring
+from feature_engine._docstrings.methods import (
+    _fit_transform_docstring,
+    _transform_imputers_docstring,
+)
 from feature_engine._docstrings.substitute import Substitution
 from feature_engine._variable_handling.init_parameter_checks import (
     _check_init_parameter_variables,
@@ -44,7 +47,7 @@ def _define_seed(
     variables_=_variables_attribute_docstring,
     feature_names_in_=_feature_names_in_docstring,
     n_features_in_=_n_features_in_docstring,
-    transform=BaseImputer._transform_docstring,
+    transform=_transform_imputers_docstring,
     fit_transform=_fit_transform_docstring,
 )
 class RandomSampleImputer(BaseImputer):