How do I sort a dictionary by value

Question

I have a dictionary of values read from two fields in a database: a string field and a numeric field. The string field is unique, so that is the key of the dictionary.

I can sort on the keys, but how can I sort based on the values?

Answer 1

It is not possible to sort a dictionary, only to get a representation of a dictionary that is sorted. Dictionaries are inherently orderless, but other types, such as lists and tuples, are not. So you need an ordered data type to represent sorted values, which will be a list—probably a list of tuples.

For instance,

import operator

x = {1: 2, 3: 4, 4: 3, 2: 1, 0: 0}

sorted_x = sorted(x.items(), key=operator.itemgetter(1))

sorted_x will be a list of tuples sorted by the second element in each tuple. dict(sorted_x) == x.

And for those wishing to sort on keys instead of values:

import operator

x = {1: 2, 3: 4, 4: 3, 2: 1, 0: 0}

sorted_x = sorted(x.items(), key=operator.itemgetter(0))