python sklearn GradientBoostingClassifier热启动报错

Question

我使用该模型在一组数据上训练了一个分类器，迭代次数为 1000 次:

clf = GradientBoostingClassifier(n_estimators=1000, learning_rate=0.05, subsample=0.1, max_depth=3)
clf.fit(X, y, sample_weight=train_weight)

现在我想将迭代次数增加到 2000。所以我这样做:

clf.set_params(n_estimators=2000, warm_start=True)
clf.fit(X, y, sample_weight=train_weight)

但是我得到以下错误:

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-13-49cfdfd6c024> in <module>()

      1 start = time.clock()
      2 clf.set_params(n_estimators=2000, warm_start=True)
----> 3 clf.fit(X, y, sample_weight=train_weight)
      4 ...

C:\Anaconda3\lib\site-packages\sklearn\ensemble\gradient_boosting.py in fit(self, X, y, sample_weight, monitor)
   1002                                     self.estimators_.shape[0]))
   1003             begin_at_stage = self.estimators_.shape[0]
-> 1004             y_pred = self._decision_function(X)
   1005             self._resize_state()
   1006 

C:\Anaconda3\lib\site-packages\sklearn\ensemble\gradient_boosting.py in _decision_function(self, X)
   1120         # not doing input validation.
   1121         score = self._init_decision_function(X)
-> 1122         predict_stages(self.estimators_, X, self.learning_rate, score)
   1123         return score
   1124 

sklearn/ensemble/_gradient_boosting.pyx in sklearn.ensemble._gradient_boosting.predict_stages (sklearn\ensemble\_gradient_boosting.c:2564)()

ValueError: ndarray is not C-contiguous

我在这里做错了什么？

Answer 1

warm_start 被正确使用。实际上有一个错误阻止了它的工作。

同时的解决方法是将数组复制到 C 连续数组:

X_train = np.copy(X_train, order='C')
X_test = np.copy(X_test, order='C')

引用:discussion和 bug