test

giorgiop · giorgiop · commit fda4e58c6bec · 2015-10-16T11:08:38.000+02:00
diff --git a/sklearn/preprocessing/tests/test_data.py b/sklearn/preprocessing/tests/test_data.py
@@ -1498,3 +1498,25 @@ def test_one_hot_encoder_unknown_transform():
     oh = OneHotEncoder(handle_unknown='42')
     oh.fit(X)
     assert_raises(ValueError, oh.transform, y)
+
+
+def test_fit_cold_start():
+    X = iris.data
+    X_2d = X[:, :2]
+
+    # Scalers that have a partial_fit method
+    scalers = [StandardScaler(with_mean=False, with_std=False),
+               MinMaxScaler(),
+               MaxAbsScaler()]
+
+    for scaler in scalers:
+        scaler.fit_transform(X)
+        # with a different shape, this may break the scaler unless the internal
+        # state is re-set
+        try:
+            scaler.fit_transform(X_2d)
+        except ValueError as err:
+            print("Cannot fit %s a second time with different shape "
+                  "of input. Error message: %s"
+                  % (scaler.__class__.__name__, str(err)))
+            assert False
