Related Articles

# Python | Subtraction of dictionaries

• Last Updated : 26 Jul, 2019

Sometimes, while working with dictionaries, we might have utility problem in which we need to perform elementary operation among the common keys of dictionaries. This can be extended to any operation to be performed. Let’s discuss subtraction of like key values and ways to solve it in this article.

Method #1 : Using dictionary comprehension + `keys()`
The combination of above two can be used to perform this particular task. This is just a shorthand to the longer method of loops and can be used to perform this task in one line.

 `# Python3 code to demonstrate working of``# Subtraction of dictionaries``# Using dictionary comprehension + keys()`` ` `# Initialize dictionaries``test_dict1 ``=` `{``'gfg'` `: ``6``, ``'is'` `: ``4``, ``'best'` `: ``7``}``test_dict2 ``=` `{``'gfg'` `: ``10``, ``'is'` `: ``6``, ``'best'` `: ``10``}`` ` `# printing original dictionaries ``print``(``"The original dictionary 1 : "` `+`  `str``(test_dict1))``print``(``"The original dictionary 2 : "` `+`  `str``(test_dict2))`` ` `# Using dictionary comprehension + keys()``# Subtraction of dictionaries``res ``=` `{key: test_dict2[key] ``-` `test_dict1.get(key, ``0``)``                       ``for` `key ``in` `test_dict2.keys()}`` ` `# printing result ``print``(``"The difference dictionary is : "` `+` `str``(res))`
Output :
```The original dictionary 1 : {'gfg': 6, 'is': 4, 'best': 7}
The original dictionary 2 : {'gfg': 10, 'is': 6, 'best': 10}
The difference dictionary is : {'gfg': 4, 'is': 2, 'best': 3}
```

Method #2 : Using `Counter() + "-" operator`
The combination of above method can be used to perform this particular task. In this, the Counter function converts the dictionary in the form in which the minus operator can perform the task of subtraction.

 `# Python3 code to demonstrate working of``# Subtraction of dictionaries``# Using Counter() + "-" operator``from` `collections ``import` `Counter`` ` `# Initialize dictionaries``test_dict1 ``=` `{``'gfg'` `: ``6``, ``'is'` `: ``4``, ``'best'` `: ``7``}``test_dict2 ``=` `{``'gfg'` `: ``10``, ``'is'` `: ``6``, ``'best'` `: ``10``}`` ` `# printing original dictionaries ``print``(``"The original dictionary 1 : "` `+`  `str``(test_dict1))``print``(``"The original dictionary 2 : "` `+`  `str``(test_dict2))`` ` `# Using Counter() + "-" operator``# Subtraction of dictionaries``temp1 ``=` `Counter(test_dict1)``temp2 ``=` `Counter(test_dict2)``res ``=` `temp2 ``-` `temp1`` ` `# printing result ``print``(``"The difference dictionary is : "` `+` `str``(``dict``(res)))`
Output :
```The original dictionary 1 : {'gfg': 6, 'is': 4, 'best': 7}
The original dictionary 2 : {'gfg': 10, 'is': 6, 'best': 10}
The difference dictionary is : {'gfg': 4, 'is': 2, '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