Friendly error on KNeighbors(n_neighbors<=0 )

xuewei4d · xuewei4d · commit d2cdcb5f121c · 2015-03-22T19:04:56.000-04:00
diff --git a/sklearn/neighbors/base.py b/sklearn/neighbors/base.py
@@ -258,6 +258,14 @@ def _fit(self, X):
         else:
             raise ValueError("algorithm = '%s' not recognized"
                              % self.algorithm)
+
+        if self.n_neighbors is not None:
+            if self.n_neighbors <= 0:
+                raise ValueError(
+                    "Expected n_neighbors > 0. Got %d" %
+                    self.n_neighbors
+                )
+
         return self
 
 
diff --git a/sklearn/neighbors/tests/test_neighbors.py b/sklearn/neighbors/tests/test_neighbors.py
@@ -834,6 +834,13 @@ def test_neighbors_badargs():
         assert_raises(ValueError,
                       nbrs.predict,
                       [])
+        if isinstance(cls, neighbors.KNeighborsClassifier) or \
+                isinstance(cls, neighbors.KNeighborsRegressor):
+            nbrs = cls(n_neighbors=-1)
+            assert_raises(ValueError,
+                      nbrs.fit,
+                      X, y)
+
 
     nbrs = neighbors.NearestNeighbors().fit(X)
 
