Python - Accessing Items in Lists Within Dictionary

Given a dictionary with values as a list, the task is to write a python program that can access list value items within this dictionary. 

Method 1: Manually accessing the items in the list

This is a straightforward method, where the key from which the values have to be extracted is passed along with the index for a specific value.

Syntax:

dictionary_name[key][index]

Example: direct indexing

Output :

['Delhi', 'Maharashtra', 'Haryana', 'Uttar Pradesh', 'Himachal Pradesh']

Delhi

Maharashtra

New Jersey

Tohoku

Method 2: Using Loop 

The easiest way to achieve the task given is to iterate over the dictionary.

Example: Using loop

Output :

India : Delhi

India : Maharashtra

India : Haryana

India : Uttar Pradesh

India : Himachal Pradesh

--------------------

Japan : Hokkaido

Japan : Chubu

Japan : Tohoku

Japan : Shikoku

--------------------

United States : New York

United States : Texas

United States : Indiana

United States : New Jersey

United States : Hawaii

United States : Alaska

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Time Complexity: O(n*n), where n is the values in dictionary
Auxiliary Space: O(1), extra constant space required

Method 3:  Accessing a particular list of the key

This is more or less the first two methods combined, where using the key the value list is iterated.

Example: Accessing a particular list of the key

Output:

Hokkaido

Chubu

Tohoku

Shikoku

Delhi

Maharashtra

Haryana

Uttar Pradesh

Himachal Pradesh

New York

Texas

Indiana

New Jersey

Hawaii

Alaska

Method 4: Using list slicing

This is a modified version of the first method, here instead of index for the value list, we pass the slicing range.

Syntax:

dictionary_name[key][start_index : end_index]

Example: using list slicing

Output :

['Delhi', 'Maharashtra', 'Haryana']

['Tohoku', 'Shikoku']

['Delhi', 'Maharashtra']

['Texas', 'Indiana', 'New Jersey', 'Hawaii']

Method 5 : Using for loop and f-string

In this approach, we will use the for loop with the f-strings to fetch the values from the dictionary. It is a little modification of the method where the normal for loop has been used. 

Step - 1 : Firstly we will iterate over the dictionary using two variables, one to point at the key and one to the values. We will also use the .items() method inside the for loop.

Step - 2: Next, as the dictionary consists of values which are of type lists so there must be more than one item in the list which we have to fetch and print. This is why we will again iterate over the second variable we took earlier to fetch each element of that particular key and print it.

Step - 3 : After printing all the elements of a certain key we will print something to separate it with the others like a line of dash(-) or dots(.).

India : Delhi
India : Maharashtra
India : Haryana
India : Uttar Pradesh
India : Himachal Pradesh
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Japan : Hokkaido
Japan : Chubu
Japan : Tohoku
Japan : Shikoku
--------------------
United States : New York
United States : Texas
United States : Indiana
United States : New Jersey
United States : Hawaii
United States : Alaska
--------------------

Time Complexity - O(n**2) # using two for loops

Space Complexity - O(1) # No extra space has been used.