title: Sklearn - Access scalar attributes after it is passed through pipeline and wrapped in GridSearchCV
body: <p>I have a pipeline and like this that I pass to GridSearchCV, how can I access the attributes of the scaler from clf?</p>
  
  <pre><code>pipe = Pipeline([
          ('scale', MinMaxScaler()),
          ('clf', tree.DecisionTreeClassifier(presort=True))
      ])
  
  pipe_param_grid = {
              'clf__min_samples_split': [2, 4, 6],
              'clf__random_state': [38, 40, 42, 44],
              'clf__max_depth': [4],
              'clf__min_samples_leaf': [2, 4],
            }
  
  clf = GridSearchCV(estimator=pipe,param_grid=pipe_param_grid)
  </code></pre>
  
  <ul>
  <li>Python: 2.7.10</li>
  <li>scikit-learn: 0.18.1</li>
  </ul>