我試圖在python 2上運行一些代碼，但我不斷收到此錯誤No module named model_selection。我檢查了一下，出于某種原因，我的python2上的sklearn是版本0.17，但是當我嘗試更新時，它說我已經(jīng)有一個更新的版本，但這是針對python 3的。我如何專門為python 2更新sklearn？運行時出現(xiàn)錯誤pip install -U scikit-learn：Requirement already up-to-date: scikit-learn in /home/ruven/anaconda3/lib/python3.6/site-packages (0.19.2)運行時出現(xiàn)錯誤python2.7 -m pip install -U scikit-learn：Collecting scikit-learn  Using cached https://files.pythonhosted.org/packages/bc/67/370aa248f54769a56216707ad7b9af19745e85a603fafa47bde353f327fb/scikit_learn-0.19.2-cp27-cp27mu-manylinux1_x86_64.whlInstalling collected packages: scikit-learn  Found existing installation: scikit-learn 0.17Cannot uninstall 'scikit-learn'. It is a distutils installed project and thus we cannot accurately determine which files belong to it which would lead to only a partial uninstall.