类型错误：“ShuffleSplit”对象不是可迭代

Question

我使用ShuffleSplit洗牌的数据，但我发现有一个错误

TypeError         Traceback (most recent call last) 
<ipython-input-36-192f7c286a58> in <module>() 
     1 # Fit the training data to the model using grid search 
----> 2 reg = fit_model(X_train, y_train) 
     3 
     4 # Produce the value for 'max_depth' 
     5 print "Parameter 'max_depth' is {} for the optimal model.".format(reg.get_params()['max_depth']) 

<ipython-input-34-18b2799e585c> in fit_model(X, y) 
    32 
    33  # Fit the grid search object to the data to compute the optimal model 
---> 34  grid = grid.fit(X, y) 
    35 
    36  # Return the optimal model after fitting the data 

/Library/Python/2.7/site-packages/sklearn/grid_search.pyc in fit(self, X, y) 
    827 
    828   """ 
--> 829   return self._fit(X, y, ParameterGrid(self.param_grid)) 
    830 
    831 

/Library/Python/2.7/site-packages/sklearn/grid_search.pyc in _fit(self, X, y, parameter_iterable) 
    571          self.fit_params, return_parameters=True, 
    572          error_score=self.error_score) 
--> 573     for parameters in parameter_iterable 
    574     for train, test in cv) 
    575 

/Library/Python/2.7/site-packages/sklearn/externals/joblib/parallel.pyc in __call__(self, iterable) 
    756    # was dispatched. In particular this covers the edge 
    757    # case of Parallel used with an exhausted iterator. 
--> 758    while self.dispatch_one_batch(iterator): 
    759     self._iterating = True 
    760    else: 

/Library/Python/2.7/site-packages/sklearn/externals/joblib/parallel.pyc in dispatch_one_batch(self, iterator) 
    601 
    602   with self._lock: 
--> 603    tasks = BatchedCalls(itertools.islice(iterator, batch_size)) 
    604    if len(tasks) == 0: 
    605     # No more tasks available in the iterator: tell caller to stop. 

/Library/Python/2.7/site-packages/sklearn/externals/joblib/parallel.pyc in __init__(self, iterator_slice) 
    125 
    126  def __init__(self, iterator_slice): 
--> 127   self.items = list(iterator_slice) 
    128   self._size = len(self.items) 
    129 

/Library/Python/2.7/site-packages/sklearn/grid_search.pyc in <genexpr>((parameters,)) 
    572          error_score=self.error_score) 
    573     for parameters in parameter_iterable 
--> 574     for train, test in cv) 
    575 
    576   # Out is a list of triplet: score, estimator, n_test_samples 

TypeError: 'ShuffleSplit' object is not iterable 

而事实证明，警告

/Library/Python/2.7/site-packages/sklearn/cross_validation.py:44: DeprecationWarning: This module was deprecated in version 0.18 in favor of the model_selection module into which all the refactored classes and functions are moved. Also note that the interface of the new CV iterators are different from that of this module. This module will be removed in 0.20. "This module will be removed in 0.20.", DeprecationWarning) /Library/Python/2.7/site-packages/sklearn/grid_search.py:43: DeprecationWarning: This module was deprecated in version 0.18 in favor of the model_selection module into which all the refactored classes and functions are moved. This module will be removed in 0.20. DeprecationWarning)

的代码将导致错误

from sklearn.metrics import make_scorer 
from sklearn.tree import DecisionTreeRegressor 
from sklearn.grid_search import GridSearchCV 

而下面没有

from sklearn.model_selection import GridSearchCV 
from sklearn.tree import DecisionTreeRegressor 
from sklearn.metrics import make_scorer 

当前scikit-learn版本是0.18.1。

这是怎么发生的？

Answer 1

虽然从grid_search进口GridSearchCV这样的：

from sklearn.grid_search import GridSearchCV 

你必须得到一个警告，如下所示：

This module was deprecated in version 0.18 in favor of the model_selection module into which all the refactored classes and functions are moved. Also note that the interface of the new CV iterators are different from that of this module. This module will be removed in 0.20.

这是自我解释，并符合你正在经历。

解决方案： - 不要使用已弃用grid_search包。使用新的model_selection。