Python - Convert Lists of List to Dictionary

Python – Convert Lists of List to Dictionary

Last Updated : 22 Apr, 2020

Sometimes, while working with Python records, we can have problem in which we have data in form of Lists of list and we need to allocate certain elements as keys and certain as values to form a dictionary. This type of application can occur in data domains. Lets discuss certain ways in which this task can be performed.

Method #1 : Using loop
This is brute way in which we perform this task. In this, we iterate through the lists forming key value pairs according to required slicing.

# Python3 code to demonstrate working of 
# Convert Lists of List to Dictionary
# Using loop
  
# initializing list
test_list = [['a', 'b', 1, 2], ['c', 'd', 3, 4], ['e', 'f', 5, 6]]
  
# printing original list
print("The original list is : " + str(test_list))
  
# Convert Lists of List to Dictionary
# Using loop
res = dict()
for sub in test_list:
    res[tuple(sub[:2])] = tuple(sub[2:])
      
# printing result 
print("The mapped Dictionary : " + str(res)) 

Output :

The original list is : [[‘a’, ‘b’, 1, 2], [‘c’, ‘d’, 3, 4], [‘e’, ‘f’, 5, 6]]
The mapped Dictionary : {(‘c’, ‘d’): (3, 4), (‘e’, ‘f’): (5, 6), (‘a’, ‘b’): (1, 2)}

Method #2 : Using dictionary comprehension
This is yet another way in which this task can be performed. This is similar to above method, just a one liner alternative.

# Python3 code to demonstrate working of 
# Convert Lists of List to Dictionary
# Using dictionary comprehension
  
# initializing list
test_list = [['a', 'b', 1, 2], ['c', 'd', 3, 4], ['e', 'f', 5, 6]]
  
# printing original list
print("The original list is : " + str(test_list))
  
# Convert Lists of List to Dictionary
# Using dictionary comprehension
res = {tuple(sub[:2]): tuple(sub[2:]) for sub in test_list}
      
# printing result 
print("The mapped Dictionary : " + str(res)) 

Output :

The original list is : [[‘a’, ‘b’, 1, 2], [‘c’, ‘d’, 3, 4], [‘e’, ‘f’, 5, 6]]
The mapped Dictionary : {(‘c’, ‘d’): (3, 4), (‘e’, ‘f’): (5, 6), (‘a’, ‘b’): (1, 2)}

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