LearnToCodeWithBaseball ⚾️ 🏟️ 🧢

love baseball? Want to code? Start here. Using Python and baseball's biggest stars and stats, we'll learn variables, loops, lists, and more!

This project is in progress and open to feedback. 💡

Why Python?

Python is one of the easiest programming languages to read and write, which makes it perfect for learning to code for the first time. Python is also lightweight and great for data - Python doesn’t force you to memorize lots of symbols. You focus on what you want to do, not how complicated the language is.

Python is like learning the rules of baseball before learning advanced analytics — it builds a foundation you can grow on.

Step 1: Check if Python is already installed (macOS)

Open Terminal

Applications → Utilities → Terminal

Run:

python3 --version

What you’ll see

✅ Python 3.x.x → Python is installed

❌ command not found → we’ll install it

macOS sometimes ships with a system Python — we will NOT use python, only python3.

Step 2: Install Homebrew (recommended)

What is Homebrew? Homebrew is a popular, free, open-source package manager for macOS and Linuxthat simplifies installing, updating, and managing software from the command line.

So to install homebrew, we'll simply copy the following command in our terminal. (Open Terminal appliction)

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

After it finishes, let's verify that it was installed by checking the version.

brew --version

Step 2.2: Install Python

brew install python

Verify:

python3 --version
pip3 --version

We should see something like this:

Python 3.12.x
pip 23.x

Step 3: Set up project folder

In terminal, first, we'll navigate to our Desktop. (alternatively, we can use another location but for beginners, I recommed Desktop)

mkdir baseball_python
cd baseball_python

cd changes our directory to baseball_pyhton

Create our first file:

touch baseball.py

💥 You created your first python file! Congrats.

Step 4: Choose an editor (VS Code is recommended)

Install VSCode

Download from VSCode

Once downloaded, we can open up our project.

In your terminal window, we can simply type:

code .

The project should open in VSCode.

You can also open VSCode, select Open and select your baseball.py file.

If code doesn't work, Cmd + Shift + P -> Shell Command: Install 'Code' command

Step 5: Run your first Python program

Open baseball.py and type (or copy):

print("Hello, baseball Python!")

Step 5.2

❗️ you will need to add the Python extension in VSCode. It should prompt you when adding a python file.

In VS Code:

1. Click the Extensions icon on the left sidebar
2. Search for Python
3. Install Python

This extension gives us:

• Syntax highlighting
• Helpful error messages
• Easy run buttons

Run your file either in VSCode or in Terminal.

In VSCode, select ▶Run. The intergrated terminal should open and you should see:

Hello, baseball Python!

Or in Terminal, type:

python3 baseball.py

You'll then see:

Hello, baseball Python!

🎉 That’s it. You just ran your first Python file.

Why this matters

• print() shows output
• .py files are Python programs
• python3 filename.py runs the file in Terminal

Step 6: Install Baseball-Friendly Libaries

Python really shines when working with data, and baseball is full of it.

We’ll install a few libraries that help us work with stats.

Step 6.2: Install the libraries

pip install pandas numpy matplotlib

what these do:

• pandas → tables of player stats
• numby → math and calculations
• matplotlib → charts and graphs

Steph 6.3: Quick Test

Create a new file:

touch stats.py

Open it and add:

import pandas as pd

data = {
    "player": ["Judge", "Ohtani", "Trout"],
    "hits": [2, 3, 1],
    "at_bats": [4, 5, 3]
}

df = pd.DataFrame(data)
df["average"] = df["hits"] / df["at_bats"]

print(df)

Run it and you should see the following output:

Player	Hits	At Bats	Batting Average
Judge	2	4	0.500
Ohtani	3	5	0.600
Trout	1	3	0.333

👏 Now we're ready to code with baseball ⚾️

Step 7: Variables (using Baseball stats)

Before we can do anything interesting in Python, we need to understand variables.

What is a variable?

A variable is a named container that stores a value.

In baseball terms: *A stat (hits, at-bats, runs) is a value

*The stat name is the variable

Example: open baseball.py and replace the code with this:

player_name = "Judge"
hits = 2
at_bats = 4

Here's what's happening:

• player_name stores text (a string)
• hits stores a number
• ```at_bats```` stores a number

Using variables together

Now let’s calculate a batting average:

batting_average = hits / at_bats

print(player_name)
print(batting_average)

When we run the file, you should see:

Judge
0.5

Making the output easier to read

Python lets us format output so it looks nicer:

print(f"{player_name}'s batting average is {batting_average:.3f}")

Output:

Judge's batting average is 0.500

Why Variables matter:

• Store baseball stats
• Reuse values
• Change data without rewriting code

If Judge gets another hit, we only change one number:

hits = 3

Everything else updates automatically.

Takeaways

• Variables store information
• Numbers don’t need quotes
• Text does need quotes
• Variables make stats reusable and flexible

Step 8: Data Types (Strings vs Numbers)

Python needs to know what kind of data it’s working with.

These are called data types.

For now, we’ll focus on the two most important ones:

• Strings (text)
• Numbers (integers and decimals) Strings (text)

A string is any text wrapped in quotes.

Baseball examples:

player_name = "Judge"
team = "Yankees"
position = "RF"

Key rule:

• Strings must be inside quotes (" " or ' ')

If you forget the quotes, Python thinks it’s a variable and will throw an error.

Numbers

Numbers are used for math and do NOT use quotes.

hits = 2
at_bats = 4
batting_average = 0.500

There are two main number types you’ll see:

Integers (whole numbers)

hits = 2
at_bats = 4

Floats (decimals)

batting_average = 0.500

Why data types matter

Python treats strings and numbers very differently.

This works (math with numbers):

hits = 2
at_bats = 4
print(hits / at_bats)

Output:

0.5

This does NOT work (math with strings):

hits = "2"
at_bats = "4"
print(hits / at_bats)

❌ Python will error because text can’t be divided.

Mixing strings and numbers (the right way)

If you want to print text and numbers together, use an f-string:

player_name = "Judge"
hits = 2
at_bats = 4

average = hits / at_bats

print(f"{player_name} has a batting average of {average:.3f}")

Output:

Judge has a batting average of 0.500

Checking a variable’s data type

You can ask Python what type something is:

print(type(player_name))
print(type(hits))
print(type(average))

Output:

<class 'str'>
<class 'int'>
<class 'float'>

Common beginner mistake 🚨

❌ This looks right but is wrong:

hits = "2"

✅ This is correct:

hits = 2

Remember:

• Quotes = text
• No quotes = number

Key takeaways

• Strings = text (names, teams, positions)
• Integers = whole numbers (hits, at-bats)
• Floats = decimals (averages)
• Python needs correct data types to do math

Step 9: Lists (storing a roster)

So far, we’ve worked with one player at a time. But baseball is a team sport — we need a way to store multiple players together.

That’s where lists come in.

Creating a List

players = ["Judge", "Ohtani", "Trout"]

Things to remember:

• Lists use square brackets []
• Items are separated by commas
• Order matters

Accessing items in a list

Each item in a list has a position called an index. Indexes start at 0, not 1.

print(players[0])
print(players[1])
print(players[2])

Output:

Judge
Ohtani
Trout

Adding players to a list

You can add a new player to the roster using .append() :

players.append("Betts")
print(players)

Output:

['Judge', 'Ohtani', 'Trout', 'Betts']

Counting players on the roster

To see how many players are in the list, use len() :

print(len(players))

Output:

4

Lists of numbers (baseball stats)

Lists aren’t just for names — they’re great for stats too:

hits = [2, 3, 1]
at_bats = [4, 5, 3]

Each position lines up with the same player:

• hits[0] → Judge
• hits[1] → Ohtani
• hits[2] → Trout

Using list values in calculations

average = hits[0] / at_bats[0]
print(average)

Output:

0.5

Common beginner mistakes 🚨

❌ Using parentheses instead of brackets:

players = ("Judge", "Ohtani", "Trout")

❌ Forgetting indexes start at 0:

print(players[1])

(This prints the second player, not the first.)

Key takeaways

• Lists store multiple values
• Lists use square brackets
• Indexes start at 0
• Lists are perfect for rosters and stat groups