Python pip安装包的问题记录

因为Mac系统自带2.7.3的python，就没打算用3.x

然后使用系统自带的python安装一些包的时候，由于Mac系统的sip系统完整性保护，不允许我卸载系统自带的已经过时的包，因此无法更新安装。

后来就在stack overflow上找到了一个类似情况，使用

sudo pip install xxx --upgrade --ignore-installed xx

之后安装scikit-learn的时候，没有sudo，结果报了下面的错

pip install -U scikit-learn
Collecting scikit-learn
Downloading scikit_learn-0.18.2-cp27-cp27m-macosx_10_6_intel.macosx_10_9_intel.macosx_10_9_x86_64.macosx_10_10_intel.macosx_10_10_x86_64.whl (7.5MB)
100% |████████████████████████████████| 7.5MB 87kB/s
Installing collected packages: scikit-learn
Exception:
Traceback (most recent call last):
File "/Library/Python/2.7/site-packages/pip-9.0.1-py2.7.egg/pip/basecommand.py", line 215, in main
status = self.run(options, args)
File "/Library/Python/2.7/site-packages/pip-9.0.1-py2.7.egg/pip/commands/install.py", line 342, in run
prefix=options.prefix_path,
File "/Library/Python/2.7/site-packages/pip-9.0.1-py2.7.egg/pip/req/req_set.py", line 784, in install
**kwargs
File "/Library/Python/2.7/site-packages/pip-9.0.1-py2.7.egg/pip/req/req_install.py", line 851, in install
self.move_wheel_files(self.source_dir, root=root, prefix=prefix)
File "/Library/Python/2.7/site-packages/pip-9.0.1-py2.7.egg/pip/req/req_install.py", line 1064, in move_wheel_files
isolated=self.isolated,
File "/Library/Python/2.7/site-packages/pip-9.0.1-py2.7.egg/pip/wheel.py", line 345, in move_wheel_files
clobber(source, lib_dir, True)
File "/Library/Python/2.7/site-packages/pip-9.0.1-py2.7.egg/pip/wheel.py", line 316, in clobber
ensure_dir(destdir)
File "/Library/Python/2.7/site-packages/pip-9.0.1-py2.7.egg/pip/utils/__init__.py", line 83, in ensure_dir
os.makedirs(path)
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 157, in makedirs
mkdir(name, mode)
OSError: [Errno 13] Permission denied: '/Library/Python/2.7/site-packages/scikit_learn-0.18.2.dist-info'

提示无法mkdir，加了个sudo解决问题。