[Tutor] Sorting Dictionary of Dictionary by certain Value

[Bill Campbell]

On Wed, Sep 24, 2008, John Fouhy wrote:
>2008/9/24 Joe Python <jopython at gmail.com>:
>> Hi Pythonistas,
>>
>> I have a large dictionary of dictionary (50,000+ keys) which has a structure
>> as follows:
>[snip]
>> I want to sort the dictionary by 'income'
>> Is there an efficient way to do the same.
>
>Note that you cannot sort a dictionary.  The best you can do is build
>a list containing the dictionary keys in the appropriate order and use
>the dictionary in combination with that list.

What you can do is create a class for the objects in the top
level dictionary, and create a __cmp__ method in that class using
cmp to compare the objects in the dictionary, finally sorting the
values.

class MyStuff(object):
    def __init__(self, name, income):
        self.name = name
        self.income = int(income)
    def cmp(self, other):
        return(cmp((-self.income, self.name), -other.income, other.name))

d = dict(
    key1 = MyStuff('john', 10000),
    key2 = MyStuff('bill', 20000),
)

vals = d.values()
vals.sort()
# vals should be sorted by income in descending order and name.

Bill
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