[ Python 常見問題 ] How to list imported modules?

Source From Here 
Question 
How to enumerate all imported modules? E.g. I would like to get ['os', 'sys'] for from this code: 

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1. import os  
2. import sys  

How-To 
You can leverage Python std library sys.modules: 

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1. # -*- coding: utf-8 -*-    
2. import sys  
3. import os  
4.   
5. imported_modules = sys.modules.keys()  
6. print "Total {0} modules being imported:".format(len(imported_modules))  
7. for m in ["os", "sys", "struct"]:  
8.     print "\tIncluding {0}? {1}".format(m, m in imported_modules)​​​  

Execution Result: 

Total 48 modules being imported:
Including os? True
Including sys? True
Including struct? False

An approximation of getting all imports for the current module only would be to inspect globals() (Return a dictionary representing the current global symbol table. This is always the dictionary of the current module) for modules: 

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1. # -*- coding: utf-8 -*-    
2. import sys  
3. import os  
4. import types  
5.   
6. def imports():  
7.     for name, val in globals().items():  
8.         if isinstance(val, types.ModuleType):  
9.             yield val.__name__  
10.   
11. for m in imports():  
12.     print "{0}".format(m)  

Execution Result 

__builtin__
sys
os
types

This won't return local imports, or non-module imports like from x import y. Note that this returns val.__name__ so you get the original module name if you usedimport module as alias; yield name instead if you want the alias.