Skip to content
Related Articles

Related Articles

Python | Increment value in dictionary
  • Last Updated : 26 Jul, 2019

Sometimes, while working with dictionaries, we can have a use-case in which we require to increment a particular key’s value in dictionary. It may seem a quite straight forward problem, but catch comes when the existence of a key is not known, hence becomes a 2 step process at times. Let’s discuss certain ways in which this task can be performed.

Method #1 : Using get()
The get function can be used to initialize a non-existing key with 0 and then the increment is possible. By this way the problem of non-existing key can be avoided.




# Python3 code to demonstrate working of
# Increment value in dictionary
# Using get()
  
# Initialize dictionary
test_dict = {'gfg' : 1, 'is' : 2, 'for' : 4, 'CS' : 5}
  
# printing original dictionary
print("The original dictionary : " +  str(test_dict))
  
# Using get()
# Increment value in dictionary
test_dict['best'] = test_dict.get('best', 0) + 3
      
# printing result 
print("Dictionary after the increment of key : " + str(test_dict))
Output :

The original dictionary : {‘is’: 2, ‘CS’: 5, ‘for’: 4, ‘gfg’: 1}
Dictionary after the increment of key : {‘is’: 2, ‘CS’: 5, ‘for’: 4, ‘best’: 3, ‘gfg’: 1}

 



Method #2 : Using defaultdict()
This problem can also be solved by using a defaultdict method, which initializes the potential keys and doesn’t throw an exception in case of non-existence of keys.




# Python3 code to demonstrate working of
# Increment value in dictionary
# Using defaultdict()
from collections import defaultdict
  
# Initialize dictionary
test_dict = defaultdict(int)
  
# printing original dictionary
print("The original dictionary : " +  str(dict(test_dict)))
  
# Using defaultdict()
# Increment value in dictionary
test_dict['best'] += 3
      
# printing result 
print("Dictionary after the increment of key : " + str(dict(test_dict)))
Output :

The original dictionary : {}
Dictionary after the increment of key : {‘best’: 3}

 Attention geek! Strengthen your foundations with the Python Programming Foundation Course and learn the basics.  

To begin with, your interview preparations Enhance your Data Structures concepts with the Python DS Course. And to begin with your Machine Learning Journey, join the Machine Learning – Basic Level Course

My Personal Notes arrow_drop_up
Recommended Articles
Page :