Python Program to create a List using custom key-value pair of a dictionary

Given a dictionary list, the task here is to write a python program that can convert it to a dictionary with items from values of custom keys.

Input : test_list = [{‘gfg’ : 1, ‘is’ : 4, ‘best’ : 6},

             {‘gfg’ : 10, ‘is’ : 3, ‘best’ : 7},

             {‘gfg’ : 9, ‘is’ : 4, ‘best’ : 2},

             {‘gfg’ : 4, ‘is’ : 1, ‘best’ : 0},

             {‘gfg’ : 6, ‘is’ : 3, ‘best’ : 8}], key, value = ‘gfg’, ‘best’

Output : {1: 6, 10: 7, 9: 2, 4: 0, 6: 8}

Explanation : Dictionary with ‘gfg”s keys and ‘best”s values is constructed.

Input : test_list = [{‘gfg’ : 1, ‘is’ : 4, ‘best’ : 6},

             {‘gfg’ : 10, ‘is’ : 3, ‘best’ : 7},

             {‘gfg’ : 9, ‘is’ : 4, ‘best’ : 2}], key, value = ‘gfg’, ‘best’

Output : {1: 6, 10: 7, 9: 2}

Explanation : Dictionary with ‘gfg”s keys and ‘best”s values is constructed.

Method 1 : Using loop

In this, dictionary list is iterated and values of required custom keys are extracted to declare key value pairs of result dictionary.

Example:

Python3

# initializing list
test_list = [{'gfg': 1, 'is': 4, 'best': 6},
             {'gfg': 10, 'is': 3, 'best': 7},
             {'gfg': 9, 'is': 4, 'best': 2},
             {'gfg': 4, 'is': 1, 'best': 0},
             {'gfg': 6, 'is': 3, 'best': 8}]

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

# initializing key-values
key, value = 'gfg', 'best'

res = dict()
for sub in test_list:

    # constructed values
    res[sub[key]] = sub[value]

# printing result
print("Dictionary values : " + str(res))

Output:

The original list is : [{‘gfg’: 1, ‘is’: 4, ‘best’: 6}, {‘gfg’: 10, ‘is’: 3, ‘best’: 7}, {‘gfg’: 9, ‘is’: 4, ‘best’: 2}, {‘gfg’: 4, ‘is’: 1, ‘best’: 0}, {‘gfg’: 6, ‘is’: 3, ‘best’: 8}]

Dictionary values : {1: 6, 10: 7, 9: 2, 4: 0, 6: 8}

Method 2 : Using dictionary comprehension

In this, we perform similar task as above method, difference being dictionary comprehension is used to offer one liner alternative to solution.

Example:

Python3

# initializing list
test_list = [{'gfg': 1, 'is': 4, 'best': 6},
             {'gfg': 10, 'is': 3, 'best': 7},
             {'gfg': 9, 'is': 4, 'best': 2},
             {'gfg': 4, 'is': 1, 'best': 0},
             {'gfg': 6, 'is': 3, 'best': 8}]

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

# initializing key-values
key, value = 'gfg', 'best'

# dictionary comprehension for one liner
res = {sub[key]: sub[value] for sub in test_list}

# printing result
print("Dictionary values : " + str(res))

Output:

The original list is : [{‘gfg’: 1, ‘is’: 4, ‘best’: 6}, {‘gfg’: 10, ‘is’: 3, ‘best’: 7}, {‘gfg’: 9, ‘is’: 4, ‘best’: 2}, {‘gfg’: 4, ‘is’: 1, ‘best’: 0}, {‘gfg’: 6, ‘is’: 3, ‘best’: 8}]

Dictionary values : {1: 6, 10: 7, 9: 2, 4: 0, 6: 8}