Python - Create dictionary from the list

Python – Create dictionary from the list

Last Updated : 01 Oct, 2020

Given a list. The task is to convert it to a dictionary with the values as the list element and keys as the concatenation of the given string K and value.

Examples:

Input : test_list = [“gfg”, “is”, “best”], K = “pref_”
Output : {‘pref_gfg’: ‘gfg’, ‘pref_is’: ‘is’, ‘pref_best’: ‘best’}
Explanation : Keys constructed after concatenating K.

Input : test_list = [“gfg”, “best”], K = “pref_”
Output : {‘pref_gfg’: ‘gfg’, ‘pref_best’: ‘best’}
Explanation : Keys constructed after concatenating K.

Method #1: Using loop

This is one of the ways in which this task can be performed. In this, we perform concatenation using + operator to construct keys and values are extracted from list.

Python3

# Python3 code to demonstrate working of  
# Values derived Dictionary keys 
# Using loop 
  
# initializing list 
test_list = ["gfg", "is", "best"]  
  
# printing original list 
print("The original list is : " + str(test_list)) 
  
# initializing K  
K = "def_key_"
  
# using loop to construct new Dictionary 
# + operator used to concat default key and values  
res = dict() 
for ele in test_list: 
    res[K + str(ele)] = ele  
  
# printing result  
print("The constructed Dictionary : " + str(res)) 

Output:

The original list is : [‘gfg’, ‘is’, ‘best’]
The constructed Dictionary : {‘def_key_gfg’: ‘gfg’, ‘def_key_is’: ‘is’, ‘def_key_best’: ‘best’}

Method #2: Using dictionary comprehension

This is yet another way in which this task can be performed. In this, we construct a dictionary using one-liner using dictionary comprehension.

Python3

# Python3 code to demonstrate working of  
# Values derived Dictionary keys 
# Using dictionary comprehension 
  
# initializing list 
test_list = ["gfg", "is", "best"]  
  
# printing original list 
print("The original list is : " + str(test_list)) 
  
# initializing K  
K = "def_key_"
  
# using dictionary comprehension 
# + operator used to concat default key and values  
res = {K + str(ele) : ele for ele in test_list} 
  
# printing result  
print("The constructed Dictionary : " + str(res))