Ubuntu最简单方法更换Python3.x版本

快速安装python3，安装最新pip的简单方法：
Ubuntu自带python2.7，在我们实际使用中，会需要用到python3.x。今天就在这里写一个详细简单的更换python3.5的方法。建议切换3.5，因为这能从阿里源直接下，比那些ppa要快很多。

1.更换阿里源（又快又稳）

1. 首先输入

 vim /etc/apt/sources.list

3. 在编辑器中删掉之前所有内容，把下面内容粘贴上去：

deb-src http://archive.ubuntu.com/ubuntu xenial main restricted #Added by software-properties
deb http://mirrors.aliyun.com/ubuntu/ xenial main restricted
deb-src http://mirrors.aliyun.com/ubuntu/ xenial main restricted multiverse universe #Added by software-properties
deb http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted multiverse universe #Added by software-properties
deb http://mirrors.aliyun.com/ubuntu/ xenial universe
deb http://mirrors.aliyun.com/ubuntu/ xenial-updates universe
deb http://mirrors.aliyun.com/ubuntu/ xenial multiverse
deb http://mirrors.aliyun.com/ubuntu/ xenial-updates multiverse
deb http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse #Added by software-properties
deb http://archive.canonical.com/ubuntu xenial partner
deb-src http://archive.canonical.com/ubuntu xenial partner
deb http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted multiverse universe #Added by software-properties
deb http://mirrors.aliyun.com/ubuntu/ xenial-security universe
deb http://mirrors.aliyun.com/ubuntu/ xenial-security multiverse

2.安装python3.5

1. 更新

  
  sudo apt update

2. 然后安装

  sudo apt-get install python3.5

3. 版本切换

1. 关于的具体用法不在这里详细说，直接上操作, 这样你的默认python就变成了3.5

sudo update-alternatives --install /usr/bin/python python /usr/bin/python2 100

sudo update-alternatives --install /usr/bin/python python /usr/bin/python3.5 200

2. 如果你还想切换回来：按照图片中提示来即可

sudo update-alternatives --config python

4.安装最新pip

wget https://bootstrap.pypa.io/get-pip.py

sudo python3 get-pip.py

sudo pip3 install setuptools --upgrade