python2和python3的train_test_split

python2 sklearn.cross_validation.train_test_split python3 sklearn.model_selection.train_test_split

在进行cross-validation的时候导入sklearn.cross_validation import train_test_split 发现出现了一个DeprecationWarning（弃用警告）

warning message：

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)

意思是cross_validation模块在0.18版本中被弃用，现在已经被model_selection代替。所以在导入的时候把sklearn.cross_validation import train_test_split更改为 from sklearn.model_selection import train_test_split

这个模块在版本0.18中被弃用，有利于所有重构的类和函数被移动到的model_selection模块。 还要注意，新的CV迭代器的接口不同于这个模块的接口。 这个模块将在0.20中删除。

如果调用sklearn的model_selection时，发现sklearn中没有model_selection的模块，则需要进行对sklearn版本进行升级。