Don't use floats to index numpy arrays

sklearn/feature_selection/rfe.py

@@ -6,7 +6,6 @@
 
 """Recursive feature elimination for feature ranking"""
 
-import warnings
 import numpy as np
 from ..utils import check_X_y, safe_sqr
 from ..utils.metaestimators import if_delegate_has_method
@@ -135,7 +134,7 @@ class RFE(BaseEstimator, MetaEstimatorMixin, SelectorMixin):
         # Initialization
         n_features = X.shape[1]
         if self.n_features_to_select is None:
-            n_features_to_select = n_features / 2
+            n_features_to_select = n_features // 2
         else:
             n_features_to_select = self.n_features_to_select