Inheritance in OnehotTransactions (#249)

rasbt · Sep 19, 2017 · 958cb83 · 958cb83
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diff --git a/docs/sources/CHANGELOG.md b/docs/sources/CHANGELOG.md
@@ -21,10 +21,11 @@ The CHANGELOG for the current development version is available at
 
 - The `'support'` column returned by `frequent_patterns.association_rules` was changed to compute the support of "antecedant union consequent", and new `antecedant support'` and `'consequent support'` column were added to avoid ambiguity. [#245](https://github.com/rasbt/mlxtend/pull/245)
 - Added `'leverage'` and `'conviction` as evaluation metrics to the `frequent_patterns.association_rules` function. [#246](https://github.com/rasbt/mlxtend/pull/246) & [#247](https://github.com/rasbt/mlxtend/pull/247)
+- Allow the `OnehotTransactions` to be cloned via scikit-learn's `clone` function, which is required by e.g., scikit-learn's `FeatureUnion` or `GridSearchCV` (via [Iaroslav Shcherbatyi](https://github.com/iaroslav-ai)). [#249](https://github.com/rasbt/mlxtend/pull/249)
 
 ##### Bug Fixes
 
-- 
+- Allow `OneHot`
 
 
 ### Version 0.8.0 (2017-09-09)

diff --git a/mlxtend/preprocessing/onehot.py b/mlxtend/preprocessing/onehot.py
@@ -5,6 +5,7 @@
 # License: BSD 3 clause
 
 import numpy as np
+from sklearn.base import BaseEstimator, TransformerMixin
 
 
 def one_hot(y, num_labels='auto', dtype='float'):
@@ -51,7 +52,7 @@ def one_hot(y, num_labels='auto', dtype='float'):
     return ary.astype(dtype)
 
 
-class OnehotTransactions(object):
+class OnehotTransactions(BaseEstimator, TransformerMixin):
     """One-hot encoder class for transaction data in Python lists
 
     Parameters

diff --git a/mlxtend/preprocessing/tests/test_onehot_transactions.py b/mlxtend/preprocessing/tests/test_onehot_transactions.py
@@ -6,6 +6,8 @@
 
 import numpy as np
 from mlxtend.preprocessing import OnehotTransactions
+from sklearn.base import clone
+from mlxtend.utils import assert_raises
 
 
 dataset = [['Apple', 'Beer', 'Rice', 'Chicken'],
@@ -63,3 +65,19 @@ def test_inverse_transform():
     oht.fit(dataset)
     np.testing.assert_array_equal(np.array(data_sorted),
                                   np.array(oht.inverse_transform(expect)))
+
+
+def test_cloning():
+
+    oht = OnehotTransactions()
+    oht.fit(dataset)
+    oht2 = clone(oht)
+
+    msg = ("'OnehotTransactions' object has no attribute 'columns_'")
+    assert_raises(AttributeError,
+                  msg,
+                  oht2.transform,
+                  dataset)
+
+    trans = oht2.fit_transform(dataset)
+    np.testing.assert_array_equal(expect, trans)