Kursusindhold

Introduction to Python (dev copy)

1. First Acquaintance with Python

The Very First Steps in Python How to Use Comments for Readability Perform Simple Math in Python Handle More Challenging Math in Python Bringing Python Fundamentals Together

2. Variables and Types in Python

How to Store Numbers in Python Python Naming Rules for Variables How to Work with Variables in Python Data Types in Python Challenge: Converting Kilometers to Miles Store Text with Strings in Python String Indexing in Python Negative Indexing and String Length in Python String Slicing in Python Challenge: Retrieving Letters from String String Concatenation in Python

3. Conditional Statements in Python

Boolean Data Type in Python Challenge: Working with Comparison Operators How to Combine Conditions in Python Challenge: Working with Logical Operators Membership Operators and Type Comparisons in Python How to Use if/else Expressions in Python Challenge: Running a Grocery Store Challenge: Creating Odd and Even Logic if/elif/else Expressions Challenge: Running Grocery Store Extended Challenge: Outputting Positive, Negative or Zero

4. Other Data Types in Python

Python Lists Common List Methods in Python Challenge: Updating List Nested Lists in Python Challenge: Retrieving Information from Nested List Python Tuples Common Tuple Methods in Python Challenge: Updating Tuple Nested Tuples in Python Challenge: Retrieving Information from Nested Tuple Python Dictionaries Challenge: Completing Dictionary Common Dictionary Methods in Python Challenge: Updating Dictionary

5. Loops in Python

Explore the while Loop in Python Challenge: Working with the While Loop Explore the for Loop in Python Challenge: Working with the For Loop Range Function in Python Challenge: Using the Range Function How to Iterate Over Indexes in Python Explore Nested Loops in Python

6. Functions in Python

Built-in Functions in Python Challenge: Converting Heights How to Create Functions in Pythons Challenge: Writing First Function Use of if/else Statements in Python Functions Challenge: Identifying Positive Values Functions Without Return in Python Challenge: Creating Logging Function Modifying Functions in Python Challenge: Updating Logic of the Function Lambda Functions in Python Challenge: Creating Lambda Function

Nested Lists in Python

As mentioned in the opening chapter, lists in Python can store various data types, even including other lists. What's unique about Python, compared to many other programming languages, is that these nested lists can differ in length.

Let's dive into an example. Imagine we have data about countries and their respective areas. Instead of jamming all that information into a single list, it would be more organized to have a distinct list for each country.


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# Two-dimensional list
countries_2d = [["USA", 9629091], ["Canada", 9984670], ["Germany", 357114]]
print(countries_2d)

As illustrated, every country has its dedicated list nested within the primary list. Now, you might wonder, how do we navigate through such a structure? If we're dealing with a two-dimensional list, its elements are also lists. And, we can access the inner list's items using indexing.

Consider a two-dimensional list named countries_2d that contains 3 main elements (which are lists). Each of these lists has 2 items.

So, countries_2d[1] fetches the second list in the main list (keep in mind, Python indexing begins at 0). Moreover, countries_2d[1][0] retrieves the first item within that second list.

Check out the example below for clarity.


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# Two-dimensional list
countries_2d = [['USA', 9629091], ['Canada', 9984670], ['Germany', 357114]]

# Pull elements
print(countries_2d[1])
print(countries_2d[1][0])

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Sektion 4. Kapitel 4