Dictionaries and Tuples

Dictionaries have a method called items that returns a list of tuples, where each tuple is a key-value pair.

d = {'a':10, 'b':20, 'c': 30}
t = d.items()
print t
[('a', 10), ('c', 30), ('b', 20)]

As you can see from previous example, the items are in no particular order. So in this example we’ve started from defining a dictionary and then using built in function itmes() transformed the dictionary in into a tuple. Since the list of tuples is a list we can apply sort function on a list of tuples. Converting a dictionary to a list of tuples is a way to output the contents of a dictionary sorted by key. 

d = {'a':10, 'b':20, 'c': 30}
t = d.items()
print "t = " + str(t)
t.sort()
print "list of tuples using sort() function"
print " t = " + str(t)

The output of previous example is given below.

t = [('a', 10), ('c', 30), ('b', 20)]
list of tuples using sort() function
t = [('a', 10), ('b', 20), ('c', 30)]

The new list is sorted in ascending order by the key value.