如何安装matplotlib?[巨蟒]

我想安装时遇到问题 matplotlib 通过PIP:
我做到了:

$ sudo pip install matplotlib

出:

Requirement already satisfied: matplotlib in /usr/lib/python2.7/dist-packages (1.5.1)
launchpadlib 1.10.3 requires testresources, which is not installed.
paramiko 2.4.1 has requirement cryptography>=1.5, but you'll have cryptography 1.2.3 which is incompatible.

所以我就这么做了:

$ sudo pip install cryptography

出去: 错误同上。

代码部分:

import sys
print(sys.version)
import matplotlib.pyplot as plt

出去:

2.7.12 (default, Dec  4 2017, 14:50:18) 
Traceback (most recent call last):
[GCC 5.4.0 20160609]

import matplotlib.pyplot as plt
ImportError: No module named matplotlib.pyplot

我该怎么办?

提前谢谢。