Maximum key value from dictionary

Question

I have a python dictionary with values

d = {'A': 0, 'B': 1, 'C': 0, 'D': 4}

result = max(d.iteritems(), key=lambda x: x[1])

result = ('D', 4)

Now if there is no maximum value and all values are equal, then result should be by alphabetical order (ascending) of keys.

ie

 d = {'A': 0, 'B': 1, 'C': 0, 'D': 1}
 result should be  D

 d = {'A': 0, 'B': 5, 'C': 5, 'D': 1}
 result should be C

How this can be done in Python ?

I think, your desired alphabetical ordering would be called descending... — Ilja, Mar 14 '16 at 08:32
Related? [Sorting a Python list by two criteria](http://stackoverflow.com/questions/5212870/sorting-a-python-list-by-two-criteria) — GingerPlusPlus, Mar 14 '16 at 08:39

score 4 · Accepted Answer · answered Mar 14 '16 at 08:31

4

Adjust the lambda to check the key after the value (by returning a value-key pair)

>>> d = {'A': 0, 'B': 1, 'C': 0, 'D': 1}
>>> max(d.iteritems(), key=lambda x: (x[1], x[0]))
('D', 1)
>>> d = {'A': 0, 'B': 5, 'C': 5, 'D': 1}
>>> max(d.iteritems(), key=lambda x: (x[1], x[0]))
('C', 5)

answered Mar 14 '16 at 08:31

falsetru

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for explanation: a tuple is returned from the lambda, and tuples are sorted 'alphabetically' (element-wise, as strings would be character-wise) – Ilja Mar 14 '16 at 08:33
@Ilja, `x[1]` is a value, so value is comapred first. If values of two items are equal, key(`x[0]`) is compared: `(5, 'C') > (5, 'B')` – falsetru Mar 14 '16 at 08:35
yes, I meant this (it was not a question but a statement :)), but wrote it more abstract – Ilja Mar 14 '16 at 08:36
Another way to write that key function: `lambda x: x[::-1]` – PM 2Ring Mar 14 '16 at 09:36

Maximum key value from dictionary

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