Modifying Dictionaries

Part of the Logic & Flow section of Coddy's Python journey — lesson 10 of 78.

Dictionaries in Python are not static; you can modify them after they are created. You can add new key-value pairs, update existing ones, or delete them.

Adding a new key-value pair:

# Start with an empty dictionary
my_dict = {}

# Add a new key-value pair
my_dict["name"] = "Alice"
my_dict["age"] = 30

print(my_dict)
# Output: {'name': 'Alice', 'age': 30}

Updating an existing value:

# Update the age
my_dict["age"] = 31

print(my_dict)
# Output: {'name': 'Alice', 'age': 31}

Deleting a key-value pair:

# Delete the age
del my_dict["age"]

print(my_dict)
# Output: {'name': 'Alice'}

In these examples, we first add a new key-value pair to an empty dictionary. Then, we update the value of an existing key. Finally, we delete a key-value pair using the del keyword.

Challenge

Easy

Create a function named update_employee_info that takes three parameters: employee_dict (a dictionary), key (a string), and value. The function should update the employee_dict with the new key and value. If the key already exists, its value should be updated. If the key does not exist, a new key-value pair should be added. The function must return the updated dictionary.

Important: Make sure to modify the original dictionary and return it. Use the square bracket notation dict[key] = value to add or update entries.

Cheat sheet

Dictionaries in Python can be modified after creation. You can add new key-value pairs, update existing ones, or delete them.

Adding a new key-value pair:

my_dict = {}
my_dict["name"] = "Alice"
my_dict["age"] = 30

Updating an existing value:

my_dict["age"] = 31

Deleting a key-value pair:

del my_dict["age"]

Try it yourself

def update_employee_info(employee_dict, key, value):
    # Write code here

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Logic & Flow

1Variables Exploration

Constants Multiple Variable Assignments Swapping Variables Placeholder Variables Round Numbers List Casting

4Contact Book Application

Display Menu Add Contact

7Sets Part 2

Mathematical Operations Part 1 Mathematical Operations Part 2 Recap - Treasure Hunt Subsets and Supersets Iterating Over Sets Recap - Tournament Tracker

10Basic List Comprehensions

The Syntax Creating Simple Lists Adding Conditions Using Data Aggregation Recap - House Of Lists Recap - Elements Of Freedom

13Inventory Management System

Project Overview Add Item

Update Stock

Check Availability

Generate Report

2Dictionaries Part 1

What is a Dictionary?Creating a Dictionary Accessing ValuesModifying DictionariesRecap - Recipe Manager

5Advanced Decision Making

Ternary Operator Membership Checks Identity Checks Indentation Errors Recap - Vacation Filter

8Student Records Manager

Project Overview Add Student

11Advanced Functions

Returning Multiple Values Lambda Functions Part 1 Lambda Functions Part 2 Recap Challenge - Lambda Sort Recursive Functions Part 1 Recursive Functions Part 2 Recap - Sum Nested List

14Higher-Order Functions

The Map Function The Filter Function Recap - Email Validator Recap - Number Processor

3Dictionaries Part 2

Dictionary Methods Nested Dictionaries Checking for Keys Looping Through Dictionaries Recap - Frequency Counter

6Sets Part 1

What is a Set?Basic Operations Set Methods Recap - Remove Duplicates

9Advanced Data Aggregation

Using Sum Finding Minimum and Maximum Sorting Data Efficiently Recap - Dictionary Sorter

12Basic Error Handling

What is Error Handling?The Try and Except Block Handling Multiple Exceptions Recap - Shopping Cart Errors

15Final Challenges

Smart Contact Manager Word Analytics Data Transformer