Python program to sort Dictionary by Key Lengths

Last Updated : 02 May, 2023

Given Dictionary, sort by its key lengths.

Input : test_dict = {“Gfg” : 4, “is” : 1, “best” : 0, “for” : 3, “geeks” : 3}
Output : {‘is’: 1, ‘Gfg’: 4, ‘for’: 3, ‘best’: 0, ‘geeks’: 3}
Explanation : 2 < 3 = 3 < 4 < 5, are sorted lengths in order.

Input : test_dict = {“Gfg” : 4, “for” : 3, “geeks” : 3}
Output : {‘Gfg’: 4, ‘for’: 3, ‘geeks’: 3}
Explanation : 3 = 3 < 5, are sorted lengths in order.

Method #1 : Using len() + sort() + dictionary comprehension + items()

In this, we perform the task of sorting using sort(), items() is used to get tuple pair from the dictionary, len() gets the keys lengths. Then dictionary comprehension performs the task of converting back to dictionary.

Python3

   # Python3 code to demonstrate working of 
# Sort Dictionary by Key Lengths
# Using len() + sort() + dictionary comprehension + items()
 
def get_len(key):
    return len(key[0])
 
# initializing dictionary
test_dict = {"Gfg" : 4, "is" : 1, "best" : 0, "for" : 3, "geeks" : 3}
 
# printing original dictionary
print("The original dictionary is : " + str(test_dict))
 
# sorting using sort()
# external to render logic 
test_dict_list = list(test_dict.items())
test_dict_list.sort(key = get_len)
 
# reordering to dictionary
res = {ele[0] : ele[1]  for ele in test_dict_list}
 
# printing result 
print("The sorted dictionary : " + str(res)) 
 
  

Output:

The original dictionary is : {‘Gfg’: 4, ‘is’: 1, ‘best’: 0, ‘for’: 3, ‘geeks’: 3} The sorted dictionary : {‘is’: 1, ‘Gfg’: 4, ‘for’: 3, ‘best’: 0, ‘geeks’: 3}

Time complexity: O(n*logn)

Space complexity: O(1)

Method #2 : Using sorted() + lambda function + items() + dictionary comprehension

In this, we perform the task of sorting using sorted(), lambda function is used to provide the logic of getting key lengths.

Python3

   # Python3 code to demonstrate working of 
# Sort Dictionary by Key Lengths
# Using sorted() + lambda function + items() + dictionary comprehension
 
# initializing dictionary
test_dict = {"Gfg" : 4, "is" : 1, "best" : 0, "for" : 3, "geeks" : 3}
 
# printing original dictionary
print("The original dictionary is : " + str(test_dict))
 
# sorting using sorted()
# lambda fnc. to render logic 
test_dict_list = sorted(list(test_dict.items()), key = lambda key : len(key[0]))
 
# reordering to dictionary
res = {ele[0] : ele[1]  for ele in test_dict_list}
 
# printing result 
print("The sorted dictionary : " + str(res)) 
 
  

Output:

The original dictionary is : {‘Gfg’: 4, ‘is’: 1, ‘best’: 0, ‘for’: 3, ‘geeks’: 3} The sorted dictionary : {‘is’: 1, ‘Gfg’: 4, ‘for’: 3, ‘best’: 0, ‘geeks’: 3}

Method #5: Using zip() + sorted() + dictionary constructor

First, a dictionary called test_dict is initialized with 5 key-value pairs, where each key is a string and each value is an integer.
The original dictionary is printed using the print() function and the concatenation operator + to join the string “The original dictionary is : ” and the string representation of the test_dict dictionary obtained using the str() function.
The sorted() function is used to sort the keys of the test_dict dictionary by their length in ascending order. The sorted keys are assigned to the variable sorted_keys.
The zip() function is used to create a new iterable where each element is a tuple consisting of a key from the sorted_keys list and the corresponding value from the test_dict dictionary.
The list comprehension [test_dict[key] for key in sorted_keys] is used to create a list of values corresponding to the keys in the sorted_keys list, in the order specified by sorted_keys.
The dict() function is used to create a new dictionary from the tuples generated by the zip() function. This new dictionary is assigned to the variable sorted_dict.
The sorted dictionary is printed using the print() function and the concatenation operator + to join the string “The sorted dictionary : ” and the string representation of the sorted_dict dictionary obtained using the str() function.

Python3

   # initializing dictionary
test_dict = {"Gfg" : 4, "is" : 1, "best" : 0, "for" : 3, "geeks" : 3}
 
# printing original dictionary
print("The original dictionary is : " + str(test_dict))
 
# sorting dictionary by key lengths using zip() and sorted()
sorted_keys = sorted(test_dict.keys(), key=len)
sorted_dict = dict(zip(sorted_keys, [test_dict[key] for key in sorted_keys]))
 
# printing result
print("The sorted dictionary : " + str(sorted_dict))
 
  

Output

The original dictionary is : {'Gfg': 4, 'is': 1, 'best': 0, 'for': 3, 'geeks': 3} The sorted dictionary : {'is': 1, 'Gfg': 4, 'for': 3, 'best': 0, 'geeks': 3}

Time complexity: O(n*log(n)), where n is the number of items in the dictionary.

Auxiliary space: O(n), where n is the number of items in the dictionary.