Python | Concatenate dictionary value lists
Sometimes, while working with dictionaries, we might have a problem in which we have lists as it’s value and wish to have it cumulatively in single list by concatenation. This problem can occur in web development domain. Let’s discuss certain ways in which this task can be performed.
Method #1 : Using sum() + values()
This is the most recommended method and one liner to perform this task. In this, we access all list values using values() and concatenation utility is performed using sum().
# Python3 code to demonstrate working of# Concatenating dictionary value lists# Using sum() + values() # initializing dictionarytest_dict = {"Gfg" : [4, 5], "is" : [6, 8], "best" : [10]} # printing original dictionaryprint("The original dictionary is : " + str(test_dict)) # Concatenating dictionary value lists# Using sum() + values()res = sum(test_dict.values(), []) # printing result print("The Concatenated list values are : " + str(res)) |
Output :
The original dictionary is : {'Gfg': [4, 5], 'best': [10], 'is': [6, 8]}
The Concatenated list values are : [4, 5, 10, 6, 8]
Method #2 : Using chain() + * operator
This task can also be performed using the combination of these methods. In these, we just use inbuilt function of chain for concatenation to list and * operator is used to access all the list values into one.
# Python3 code to demonstrate working of# Concatenating dictionary value lists# Using chain() + * operatorfrom itertools import chain # initializing dictionarytest_dict = {"Gfg" : [4, 5], "is" : [6, 8], "best" : [10]} # printing original dictionaryprint("The original dictionary is : " + str(test_dict)) # Concatenating dictionary value lists# Using chain() + * operatorres = list(chain(*test_dict.values())) # printing result print("The Concatenated list values are : " + str(res)) |
Output :
The original dictionary is : {'Gfg': [4, 5], 'best': [10], 'is': [6, 8]}
The Concatenated list values are : [4, 5, 10, 6, 8]
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