Sorting a Dictionary in Python
Dictionary is a collection of items where each item contains a key value pair.
In this article we will discuss below sorting operations on dictionary.
- Sorting by keys
- Sorting by values
- Custom sorting algorithms – string, number
- Reversing the sorted order
Let’s discuss them with an example.
1. Sorting by keys
Example:
#dictionary a
a = {1:2 ,2:1 ,4:3 ,3:4 ,6:5 ,5:6 }
#printing a sorted list of the keys
print(sorted(a.keys()))
#printing the sorted list with items.
print(sorted(a.items()))
Output:
2. Sorting By Values
We can also use the values as well for sorting.
Example:
x = {'A':2 ,'B':1 ,'C':3 ,'D':4 ,'E':5 ,'F':6 }
print(sorted(x.values() ))
Output:
3. Custom Sorting Algorithm – String , Number
By using other arguments in the sorted method, we can also perform complex sorts
Example:
day = { 'one' : 'Mon' , 'two' : 'Tue' , 'three' : 'Wed' , 'four' : 'Thu' , 'five': 'Fri' , 'six' : 'Sat' , 'seven': 'Sun'}
print(day)
number = { 'one' : 'A' , 'two' : 'B' , 'three' : 'C' , 'four' : 'D' , 'five' : 'E' , 'six' : 'F' , 'seven' : 'G'}
print(sorted(day , key=number.__getitem__))
print([day[i] for i in sorted(day , key=number.__getitem__)])
Output:
4. Reversing The Sorted Order
Below example shows how to reverse the order of the sorted dictionary.
Example:
x = {'A':2 ,'B':1 ,'C':3 ,'D':4 ,'E':5 ,'F':6 }
print(sorted(x.values() , reverse= True))
Output:
It is much easier to work on dictionaries as they are mutable and have a search time complexity less than that of a list.
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