Python – Convert Dictionary Value list to Dictionary List

Sometimes, while working with Python Dictionaries, we can have a problem in which we need to convert dictionary list to nested records dictionary taking each index of dictionary list value and flattening it. This kind of problem can have application in many domains. Let’s discuss certain ways in which this task can be performed.

Input : test_list = [{‘Gfg’: [5, 6]}, {‘best’: [3, 1]}] 
Output : [{‘Gfg’: 5, ‘best’: 3}, {‘Gfg’: 6, ‘best’: 1}]

Input : test_list = [{‘Gfg’: [5]}] 
Output : [{‘Gfg’: 5}] 

Method #1 : Using loop
This is one of the ways in which this problem can be solved. In this, we perform the task in brute force manner iterating each list value index and designating a key to it. 

Python3

# Python3 code to demonstrate working of
# Convert Dictionary Value list to Dictionary List
# Using loop

# initializing list
test_list = [{'Gfg' : [5, 6, 5]}, {'is' : [10, 2, 3]}, {'best' : [4, 3, 1]}]

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

# Convert Dictionary Value list to Dictionary List
# Using loop
res =[{} for idx in range(len(test_list))]
idx = 0
for sub in test_list:
    for key, val in sub.items():
        for ele in val:
            res[idx][key] = ele
            idx += 1
        idx = 0

# printing result
print("Records after conversion : " + str(res))

Output : 
The original list is : [{‘Gfg’: [5, 6, 5]}, {‘is’: [10, 2, 3]}, {‘best’: [4, 3, 1]}] 
Records after conversion : [{‘Gfg’: 5, ‘is’: 10, ‘best’: 4}, {‘Gfg’: 6, ‘is’: 2, ‘best’: 3}, {‘Gfg’: 5, ‘is’: 3, ‘best’: 1}] 

Method #2 : Using list comprehension + zip()
This is yet another way in which we can perform this task. In this, we perform task in 2 steps, first, we extract all the keys and then pair up values using zip() accordingly.

Python3

# Python3 code to demonstrate working of
# Convert Dictionary Value list to Dictionary List
# Using list comprehension + zip()

# initializing list
test_list = [{'Gfg' : [5, 6, 5]}, {'is' : [10, 2, 3]}, {'best' : [4, 3, 1]}]

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

# Convert Dictionary Value list to Dictionary List
# Using list comprehension + zip()
keys = [list(sub.keys())[0] for sub in test_list]
vals = zip(*[val for sub in test_list for val in sub.values()])
res = [dict(zip(keys, val)) for val in vals]

# printing result
print("Records after conversion : " + str(res))

Output : 
The original list is : [{‘Gfg’: [5, 6, 5]}, {‘is’: [10, 2, 3]}, {‘best’: [4, 3, 1]}] 
Records after conversion : [{‘Gfg’: 5, ‘is’: 10, ‘best’: 4}, {‘Gfg’: 6, ‘is’: 2, ‘best’: 3}, {‘Gfg’: 5, ‘is’: 3, ‘best’: 1}]