How to iterate dictionary in python

A dictionary in python is a collection of key-value pairs where each key is associated with a value. It is required to loop over elements of a dictionary either to display them or to check if some key-value pair exists in it.
There are different ways to iterate through a dictionary and this article will outline them with examples.

Method 1: Using for loop
Iterate over a dictionary using any python loops such as a for loop. In every iteration, the loop variable will contain the key of dictionary entry.
You can also get the value corresponding to that key. Example,

#initialize dictionary
dict = {'google':'search', 'facebook':'social','youtube':'videos'}
# iterate dictionary with for loop
for key in dict:
    print('Key:', key, ', Value:', dict[item])

This example will print below output

Key: google , Value: search
Key: facebook , Value: social
Key: youtube , Value: videos

Method 2: Using iterator function
dict class has an inbuilt iterator which can be used to loop over a dictionary. Use __iter__() function to get the dictionary iterator.
Use a for loop to iterate over the keys of the dictionary. Example,

#initialize dictionary
dict = {'google':'search', 'facebook':'social','youtube':'videos'}
for item in dict.__iter__():
     print('Key:',item,', Value:',dict[item])

Above code produces the below output

Key: google , Value: search
Key: facebook , Value: social
Key: youtube , Value: videos

Method 3: Using items function
Inbuilt items functions returns all the items of the dictionary. Each item is a python tuple of the dictionary entry. A dictionary can be iterated using a for loop over these items. Example,

#initialize dictionary
dict = {'google':'search', 'facebook':'social','youtube':'videos'}
for item in dict.items():
    print(item)

As stated before, each value returned by items function is a tuple. Thus, if you print the type of the value using type function as shown below

for item in dict.items():
    print(type(item))

then the output is

<class ‘tuple’>
<class ‘tuple’>
<class ‘tuple’>

Method 4: Iterating using keys
dict class provides an inbuilt keys function which returns a collection of all the keys of dictionary. This method can be used to loop through dictionary by key. Example,

#initialize dictionary
dict = {'google':'search', 'facebook':'social','youtube':'videos'}
for key in dict.keys():
    print('Key:', key, ', Value:', dict[key])

Above example outputs

Key: google , Value: search
Key: facebook , Value: social
Key: youtube , Value: videos

Similar to keys function, there is a values function which can be used to access values of a dictionary as shown below.

dict = {'google':'search', 'facebook':'social','youtube':'videos'}
for value in dict.values():
    print('Value:', key)

Above example will print

Value: search
Value: social
Value: videos

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