[ Python 範例代碼 ] How to sort a Python dict (dictionary) by keys or values

來源自 這裡 
How-To 
- How to sort a dict by keys (Python 2.4 or greater): 

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1. mydict = {'carl':40,  
2.           'alan':2,  
3.           'bob':1,  
4.           'danny':3}  
5.   
6. for key in sorted(mydict.iterkeys()):  
7.     print "%s: %s" % (key, mydict[key])  

執行結果 

alan: 2
bob: 1
carl: 40
danny: 3

Taken from the Python FAQ: http://www.python.org/doc/faq/general/#why-doesn-t...t-sort-return-the-sorted-list. To sort the keys in reverse, add reverse=True as a keyword argument to the sorted function. 

- How to sort a dict by keys (Python older than 2.4): 

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1. keylist = mydict.keys()  
2. keylist.sort()  
3. for key in keylist:  
4.     print "%s: %s" % (key, mydict[key])  

The results are the same as the above. 

- How to sort a dict by value (Python 2.4 or greater): 

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1. for key, value in sorted(mydict.iteritems(), key=lambda (k,v): (v,k)):  
2.     print "%s: %s" % (key, value)  

Results: 

bob: 1
alan: 2
danny: 3
carl: 40

Taken from Nick Galbreath's Digital Sanitation Engineering blog article. 

- More Examples to sort dict by key/value 

>>> d = {'John':30, 'Allen':41, 'Ken':28, 'Mary':18}
>>> import operator
>>> sorted_d = sorted(d.items(), key=operator.itemgetter(1)) # Sorting dict items (key, value) by value
>>> sorted_d
[('Mary', 18), ('Ken', 28), ('John', 30), ('Allen', 41)]
>>> sorted(d.items(), key=operator.itemgetter(1), reverse=True) # Sorting dict items (key, value) by value in descending order
[('Allen', 41), ('John', 30), ('Ken', 28), ('Mary', 18)]
>>> sorted_d = sorted(d.items(), key=operator.itemgetter(0)) # Sorting dict items (key, value) by key
>>> sorted_d
[('Allen', 41), ('John', 30), ('Ken', 28), ('Mary', 18)]
>>> sorted(d.items(), key=operator.itemgetter(0), reverse=True)
[('Mary', 18), ('Ken', 28), ('John', 30), ('Allen', 41)]

Related posts: 
* Python data object motivated by desire for a mutab...namedtuple with default values — posted 2012-08-03 
* How to sort a list of dicts in Python — posted 2010-04-02 
* Python setdefault example — posted 2010-02-09 
* How to conditionally replace items in a list — posted 2008-08-22 
* How to use Python's enumerate and zip to iterate o...er two lists and their indices. — posted 2008-04-18 
* How to invert a dict in Python — posted 2008-01-14 
* Sort a Python dictionary by value