Python – Keys with shortest length lists in dictionary

Sometimes, while working with Python lists, we can have problem in which we need to return the keys which have minimum lengths of lists as values. This can have application in domains in which we work with data. Lets discuss certain ways in which this task can be performed. Method #1 : Using len() + loop + items() The combination of above functions can be used to perform this task. In this, we iterate the keys of dictionary and return all the keys whose lengths equates the length of smallest list using len(). 

Python3

# Python3 code to demonstrate working of
# Keys with shortest length lists in dictionary
# Using len() + loop + items()

# initializing dictionary
test_dict = {'gfg' : [4, 5],
             'is' : [9, 7, 3, 10],
             'best' : [11, 34],
             'for' : [6, 8, 2],
             'geeks' : [12, 24]}

# printing original dictionary
print("The original dictionary is : " + str(test_dict))

# Keys with shortest length lists in dictionary
# Using len() + loop + items()
min_val = min([len(test_dict[ele]) for ele in test_dict])
res = []
for ele in test_dict:
    if len(test_dict[ele]) == min_val:
        res.append(ele)

# printing result
print("The required keys are : " + str(res))

Output : 

The original dictionary is : {‘is’: [9, 7, 3, 10], ‘gfg’: [4, 5], ‘best’: [11, 34], ‘for’: [6, 8, 2], ‘geeks’: [12, 24]} The required keys are : [‘gfg’, ‘best’, ‘geeks’]

Time Complexity: O(n)
Auxiliary Space: O(n)

Method #2 : Using list comprehension This task can also be performed using a shorthand of list comprehension. In this, we perform the task similar to above task but in shorthand manner. 

Python3

# Python3 code to demonstrate working of
# Keys with shortest length lists in dictionary
# Using list comprehension

# initializing dictionary
test_dict = {'gfg' : [4, 5],
             'is' : [9, 7, 3, 10],
             'best' : [11, 34],
             'for' : [6, 8, 2],
             'geeks' : [12, 24]}

# printing original dictionary
print("The original dictionary is : " + str(test_dict))

# Keys with shortest length lists in dictionary
# Using list comprehension
min_val = min([len(test_dict[ele]) for ele in test_dict])
res = [key for key, val in test_dict.items() if len(val) == min_val]

# printing result
print("The required keys are : " + str(res))

Output : 

The original dictionary is : {‘is’: [9, 7, 3, 10], ‘gfg’: [4, 5], ‘best’: [11, 34], ‘for’: [6, 8, 2], ‘geeks’: [12, 24]} The required keys are : [‘gfg’, ‘best’, ‘geeks’]