How To Use Python Dictionary Update Method – Easy Python Guide

In this tutorial, we’ll learn how to use Python dictionary update() method with the help of multiple Python code examples.

Introduction: Python Dictionary update() Method

This method is used to update a Python dictionary by adding or updating values to it using another dictionary or by using an iterable having key/value pairs.

Syntax of update() Method

dictionaryName.update(data)

• This method takes either a dictionary as an argument or a key/value pairs iterable object(e.g. tuple).
• If the arguments are not passed then no updates will take place in dictionary.
• Python dictionary update method return None. It just updates the specified dictionary.

Example 1: Updating Values of Dictionary

dictItems={'name':'Apple','color':'Red'} 
dictItems.update({'name':'Banana'})
print(dictItems)

Output

{'name': 'Banana', 'color': 'Red'}

dictItems={'name':'Apple','color':'Red'} 
newDict={'name':'Banana'}
dictItems.update(newDict)
print(dictItems)

{'name': 'Banana', 'color': 'Red'}

Example 2: adding Item to Dictionary using update() Method

dictItems={'name':'Apple','color':'Red'} 
newDict={'number':28}
dictItems.update(newDict)
print(dictItems)

Output

{'name': 'Apple', 'color': 'Red', 'number': 28}

If the specified key passed to the Python dictionary update method is not found in the dictionary, then the same item(key and value pair) will be added to this dictionary.

Example 3: Pass Tuple using update() Method

dictItems={'name':'Apple','color':'Red'} 
tuplesList=[('color','Yellow'),('quantity',7000)]
dictItems.update(tuplesList)
print(dictItems)

Output

{'name': 'Apple', 'color': 'Yellow', 'quantity': 7000}

Example 4: update() Method Return None

dictItems={'name':'Apple'} 
print(dictItems.update({'name':'Pineapple'}))   // return None
print(dictItems)                              // updated

Output

None          // update method return none
{'name': 'Pineapple'}  // dictionary is updated