anaconda安装包错误，无法完全下载、安装

C:\Users\Default.DESKTOP-7GLG2JK>pip install -U scikit-learn

Collecting scikit-learn
  Using cached https://files.pythonhosted.org/packages/da/bf/05b08c952a73b6e7ab3700c4d2bc2d466bdfa990ef7f2d4d8a5eaa8d6c0b/scikit_learn-0.19.2-cp36-cp36m-win_amd64.whl
Installing collected packages: scikit-learn
  Found existing installation: scikit-learn 0.18.1

Cannot 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.

解决办法：pip install scikit-learn --ignore-installed scikit-learn

C:\Users\Default.DESKTOP-7GLG2JK>pip install scikit-learn --ignore-installed scikit-learn
Collecting scikit-learn
  Using cached https://files.pythonhosted.org/packages/da/bf/05b08c952a73b6e7ab3700c4d2bc2d466bdfa990ef7f2d4d8a5eaa8d6c0b/scikit_learn-0.19.2-cp36-cp36m-win_amd64.whl
Installing collected packages: scikit-learn
Successfully installed scikit-learn-0.19.2

原因：文件不完整，依赖不确定，版本升级造成的影响。

还有原先安装了sklearn，而现在已经不需要使用sklearn了，残留的文件会留在安装包的目录里，不能通过pip uninstall sklearn完全删除，所以需要手动删除sklear包。