通过字典迭代嵌套字典

Question

I have a nested dictionary as follows:

student_loan_portfolio = {
    'loan1': {'rate': .078, 'balance': 1000, 'payment': 100, 'prepayment': 0},
    'loan2': {'rate': .0645, 'balance': 10, 'payment': 5, 'prepayment': 0},
    'loan3': {'rate': .0871, 'balance': 250, 'payment': 60, 'prepayment': 0},
    'loan4': {'rate': .0842, 'balance': 200, 'payment': 37, 'prepayment': 0},
    'loan5': {'rate': .054, 'balance': 409, 'payment': 49, 'prepayment': 0},
    'loan6': {'rate': .055, 'balance': 350, 'payment': 50, 'prepayment': 0}
}

I would like to iterate through the containing dictionary (with keys loan1 through loan6 ) in order of the key containing the dictionary with the highest 'rate' value in its respective nested dictionary. That is, I would like to iterate in order of loan3 , loan4 , loan1 , loan2 , loan6 , loan5

What is the easiest way to do this?

Thanks

Answer 1

I believe you want:

sorted(student_loan_portfolio.items(), key=lambda (k,v): v['rate'], reverse=True)

(Thanks @MarkReed, you're right. To sort in descending order we need either -v['rate'] or, as I've shown above, passing reverse=True to sorted .)

Answer 2

You can sort the values like this:

sorted(student_loan_portfolio.items(), key=lambda (name,portfolio): portfolio['rate'], reverse=True) [('loan3', {'rate': 0.0871, 'balance': 250, 'payment': 60, 'prepayment': 0}), ('loan4', {'rate': 0.0842, 'balance': 200, 'payment': 37, 'prepayment': 0}), ('loan1', {'rate': 0.078, 'balance': 1000, 'payment': 100, 'prepayment': 0}), ('loan2', {'rate': 0.0645, 'balance': 10, 'payment': 5, 'prepayment': 0}), ('loan6', {'rate': 0.055, 'balance': 350, 'payment': 50, 'prepayment': 0}), ('loan5', {'rate': 0.054, 'balance': 409, 'payment': 49, 'prepayment': 0})]

See this page for more details on how to complex sorting in python works: http://wiki.python.org/moin/HowTo/Sorting/