Python Program to extract dictionaries with maximum number of keys

Given a list of dictionaries, the task is to write a python program to extract dictionary with maximum number of keys.

Input : test_list = [{‘Gfg’ : 1}, {‘Gfg’ : 1, ‘is’ : 5, ‘best’ : 4}, {‘Gfg’ : 2, ‘best’ : 9}]

Output : {‘Gfg’ : 1, ‘is’ : 5, ‘best’ : 4}

Explanation : Dictionary with max. length 3 is output.

Input : test_list = [{‘Gfg’ : 1}, {‘Gfg’ : 2, ‘best’ : 9}]

Output : {‘Gfg’ : 2, ‘best’ : 9}

Explanation : Dictionary with max. length 2 is output.

Method 1 : Using len() and loop

In this, we iterate for all the dictionaries and keep track of its number of keys, comparing and updating maximum at each step.

This method displays only the first dictionary found with maximum number of elements i.e. if more than one dictionary have the same number of elements and this number is maximum then only the first dictionary will be displayed.

Example:

Python3

# initializing list
test_list = [{'Gfg': 1}, {'Gfg': 1, 'is': 5, 'best': 4}, {'Gfg': 2, 'best': 9}]

# printing original list
print("The original list is : " + str(test_list))

res = dict()
max_len = 0
for sub in test_list:

    # comparing and updating maximum dictionary acc. to length
    if len(sub) > max_len:
        res = sub
        max_len = len(sub)

# printing result
print("Dictionary with maximum keys  : " + str(res))

Output:

The original list is : [{‘Gfg’: 1}, {‘Gfg’: 1, ‘is’: 5, ‘best’: 4}, {‘Gfg’: 2, ‘best’: 9}]

Dictionary with maximum keys  : {‘Gfg’: 1, ‘is’: 5, ‘best’: 4}

Method 2 : Using max() and list comprehension

In this, we get the maximum length of number of keys present in dictionary lists. Then dictionaries with maximum length computed are extracted. This method allows multiple results for matching keys.

Example:

Python3

# initializing list
test_list = [{'Gfg': 1}, {'Gfg': 1, 'is': 5, 'best': 4},
             {'Gfg': 2, 'best': 9, "book": 1}]

# printing original list
print("The original list is : " + str(test_list))

max_len = max(len(sub) for sub in test_list)
res = [sub for sub in test_list if len(sub) == max_len]

# printing result
print("Dictionary with maximum keys  : " + str(res))

Output:

The original list is : [{‘Gfg’: 1}, {‘Gfg’: 1, ‘is’: 5, ‘best’: 4}, {‘Gfg’: 2, ‘best’: 9, ‘book’: 1}]

Dictionary with maximum keys  : [{‘Gfg’: 1, ‘is’: 5, ‘best’: 4}, {‘Gfg’: 2, ‘best’: 9, ‘book’: 1}]