Jupyter（IPython）

Jupyter Console

Jupyter控制台，原名IPython是一个增强的Python解释器。在之前的shell中我们是利用Python解释器来执行我们的Python脚本文件，而Jupyter加强了这个shell，并添加了一些细节，简化处理数据。
通常在你写数据分析脚本时或者编写原型代码时，你需要快速测试一些代码，此时你会在shell环境下执行它，因为这样很快速。Jupyter console与Jupyter notebook 最大的区别是console是在交互模式下运行。当你输入一行代码，他就会立刻执行，然后你会看到结果。如果你想写中篇的代码片断或做数据集的深入探索，Jupyter notebook会更好。如果你想要你写测试代码，或运行快速命令，Jupyter console会更好。
Jupyter项目正处于IPython向Jupyter重塑的过程中，输入jupyter console或者ipython 即可访问jupyter控制台。

~$ ipython                                                                      
Python 3.4.3 (default, Oct 14 2015, 20:28:29)                                   
Type "copyright", "credits" or "license" for more information.                  

IPython 3.2.1 -- An enhanced Interactive Python.                                
?         -> Introduction and overview of IPython's features.                   
%quickref -> Quick reference.                                                   
help      -> Python's own help system.                                          
object?   -> Details about 'object', use 'object??' for extra details.     

In [1]: print(10)                                                               
10                                                                              

In [2]: exit      

Getting Help

Jupyter 控制台有很丰富的內建帮助系统：

• You can type ? after starting the console. This will display help about Jupyter. You can exit by typing q.
• You can type %quickref. This is a magic that will tell you some useful commands.
• If you want information about a variable, just type the name of the variable, followed by ?. ——var?
• Type help() to get access to Python help. This will enable you to get help on all the modules and functions currently available. You can quit by typing quit.
• If you want to use the Python help system to get information on a variable, type help(variable_name).——help(var)

In [3]: dq=5                                                                    

In [4]: dq?
Type:        int                                                                
String form: 5                                                                  
Docstring:                                                                      
int(x=0) -> integer                                                             
int(x, base=10) -> integer                                                      

Convert a number or string to an integer, or return 0 if no arguments           
are given.  If x is a number, return x.__int__().  For floating point           
numbers, this truncates towards zero.                                           

If x is not a number or if base is given, then x must be a string,              
bytes, or bytearray instance representing an integer literal in the                                                                         
# 输入q退出                                                                                
In [5]: help(dq)  
# 输入quit退出  
# 输入exit退出Jupyter 

Persistent Sessions

与 Jupyter notebook一样，当你第一次加载Jupyter console时会启动一个内核会话（kernel session）。每次在控制台中运行代码时，将会把变量存储在这个会话中，使得你下面运行的代码可以访问这些变量。

~$ ipython                                                                      
Python 3.4.3 (default, Oct 14 2015, 20:28:29)                                   
Type "copyright", "credits" or "license" for more information.                  

IPython 3.2.1 -- An enhanced Interactive Python.                                
?         -> Introduction and overview of IPython's features.                   
%quickref -> Quick reference.                                                   
help      -> Python's own help system.                                          
object?   -> Details about 'object', use 'object??' for extra details.          

~$ ipython                                                                      
Python 3.4.3 (default, Oct 14 2015, 20:28:29)                                   
Type "copyright", "credits" or "license" for more information.                  

IPython 3.2.1 -- An enhanced Interactive Python.                                
?         -> Introduction and overview of IPython's features.                   
%quickref -> Quick reference.                                                   
help      -> Python's own help system.                                          
object?   -> Details about 'object', use 'object??' for extra details.          

In [1]: dq = 5                                                                  

In [2]: dq_10 = dq * 10                                                         

In [3]: exit       

Jupyter Magics

%quickref是 Jupyter种一种特殊的命令（Magics ），总是以% 开头，它们使你能够在Python没有执行你的命令前访问Jupyter的特殊功能。下面是一些特殊的magics ：

• %run – allows you to run an external Python script. Any variables in the script will be stored in the current kernel session.
• %edit – opens a file editor. Any code you type into the editor will be executed by Jupyter when you exit the editor.
• %debug – if there’s an error in any of your code, running %debug afterwards will open an interactive debugger you can use to trace the error.
• %history – shows you the last few commands you ran.
• %save – saves the last few commands you ran to a file.
• %who – print all the variables in the session.
• %reset – resets the session, and removes all stored variables.

# 新建一个zm.py的脚本，添加了一个变量，一个打印语句
if __name__=="__main__":                                                        
    zm = "ZM is a good programmer"                                              
    print(zm)   

• 在ipython中使用%run执行这个文本，使用%who来查看变量：

In [1]: %run zm.py                                                              
ZM is a good programmer 
In [2]: %who                                                                    
zm  

• 在使用%who查看变量之前，首先要是有%run来执行一个脚本，然后%who显示的就是刚刚执行的那个脚本中的变量。

Autocompletion

Autocompletion（自动补全）：当你输入一个变量名称时，按TAB键可以自动匹配所有的变量，自动补全剩余的字符。If you hit TAB after typing a variable name, Jupyter will show you the methods on the variable.

# 输入字母a之后按TAB键，自动回车显示所有匹配的变量名以及函数名
In [1]: a                                                                       
%alias        %autoindent   all           as                                    
%alias_magic  %automagic    and           ascii                                 
%autocall     abs           any           assert      

Accessing The Shell

• 可以在Jupyter 中运行shell命令，只要在命令的前面加上！就可以。比如！ls会显示当前Jupyter 所在目录的所有文件：

In [1]: !ls                                                                     

In [2]: !whoami                                                                 
dq                                                                              

In [3]: !ls -a                                                                  
.  ..  .bashrc  .byobu  .cache  .ipython  .tmux.conf                            

In [4]: 

Pasting In Code

在python采用复制时不会复制缩进，因此粘贴时会出现错误。因此需要使用paste magics：

• %cpaste – opens a special editing area where you can paste in code normally, without whitespace being a problem. You can type –
  alone on a line to exit. After you exit, any code you pasted in will
  be immediately executed.
• %paste – takes code from your clipboard and runs it in Jupyter. This doesn’t work on remote systems, where Jupyter doesn’t
  have access to your clipboard.

# 首先将下面这段代码复制到剪切板
for i in range(10):
    if i < 5:
        print(i)
    else:
        print(i * 2)
# 打开ipython，然后在其中输入%cpaste
# 再输入--退出时你的程序就会被执行。

Next Steps

Some specific explorations you can try:

• Explore more of the magics.
• Try using Jupyter to debug exceptions.
• Develop a Python script locally, and see if Jupyter can help with your workflow.