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This seems like it has to be a dupe but my SO-searching-fu is poor today...
Say I have a dictionary of integer key/values, how can I sort the dictionary by the values descending, then by the key descending (for common values).
Input:
{12:2, 9:1, 14:2} {100:1, 90:4, 99:3, 92:1, 101:1} Output:
[(14,2), (12,2), (9,1)] # output from print [(90,4), (99,3), (101,1), (100,1), (92,1)] 
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To sort a dictionary by value then the key we can easily use the lambda and sorted function. In this example, we can set this reverse flag order as true which means the value will be in descending order.
The key=lambda x: (x[1],x[0]) tells sorted that for each item x in y. items() , use (x[1],x[0]) as the proxy value to be sorted. Since x is of the form (key,value) , (x[1],x[0]) yields (value,key) .
To sort a dictionary by value in Python you can use the sorted() function. Python's sorted() function can be used to sort dictionaries by key, which allows for a custom sorting method. sorted() takes three arguments: object, key, and reverse. Dictionaries are unordered data structures.
Dictionaries are made up of key: value pairs. Thus, they can be sorted by the keys or by the values.
In [62]: y={100:1, 90:4, 99:3, 92:1, 101:1} In [63]: sorted(y.items(), key=lambda x: (x[1],x[0]), reverse=True) Out[63]: [(90, 4), (99, 3), (101, 1), (100, 1), (92, 1)] The key=lambda x: (x[1],x[0]) tells sorted that for each item x in y.items(), use (x[1],x[0]) as the proxy value to be sorted. Since x is of the form (key,value), (x[1],x[0]) yields (value,key). This causes sorted to sort by value first, then by key for tie-breakers.
reverse=True tells sorted to present the result in descending, rather than ascending order.
See this wiki page for a great tutorial on sorting in Python.
PS. I tried using key=reversed instead, but reversed(x) returns an iterator, which does not compare as needed here.
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