Python dictionary update() usage and example

Python dictionary methods

The update() method inserts the specified items into the dictionary. This specified item can be a dictionary or an iterable object.

If the key is not in the dictionary, the update() method will add the element to the dictionary. If the key is in the dictionary, it will use the new value to update the key.

The syntax of update() is:

dict.update([other])

The parameters of update()

The update() method takesdictionaryor key/key-value pairs (usuallytupleAn iterable object of

If update() is called without passing any parameters, the dictionary remains unchanged.

The return value of update()　

The update() method uses a dictionary object or key/Elements of an iterable object containing key-value pairs update the dictionary.

It does not return any value (returns None).

Example1: how update() works in Python?

d = {1: 'one',　2: 'three'}
d1　= {2: 'two'}
# Update key=2value
d.update(d1)
print(d)
d1　= {3: 'three'}
# Use key3Add elements
d.update(d1)
print(d)

When running this program, the output is:

{1: 'one',　2: 'two'}
{1: 'one',　2: 'two',　3: 'three'

Example2: how to use update() with Iterable?

d = {'x':　2}
d.update(y =　3, z = 0)
print(d)

When running this program, the output is:

{'x':　2, 'y':　3, 'z': 0}

Python dictionary methods