Working with strings

Introduction to Python for Developers

Jasmin Ludolf

Senior Data Science Content Developer

Strings are everywhere!

Hello written with string

Displaying messages

Processing text input

File names

Formatting output

Handling data

¹ Image generated by ChatGPT

Python knows single and double quotes

# This works
ingredient_name = 'San Marzano tomatoes'

# This also works
ingredient_name = "San Marzano tomatoes"

' = apostrophe = single quote

Advantages of double quotes

# Single quote string variable containing an apostrophe
ingredient_name = 'Chef's special seasoning'
print(ingredient_name)

SyntaxError: invalid syntax.

# Double quote string variable containing an apostrophe
ingredient_name = "Chef's special seasoning"
print(ingredient_name)

Chef's special seasoning

Sentences and paragraphs

recipe_step = "Heat olive oil in a large pan and sauté garlic until fragrant"

Multi-line strings

# Create a string variable over multiple lines
recipe_instructions = """1. Bring a large pot of salted water to boil and cook pasta
2. Heat olive oil in a pan and sauté minced garlic until fragrant
3. Add chopped tomatoes and simmer for 10 minutes
4. Toss cooked pasta with tomato sauce and fresh basil leaves
"""

"""text""": Multi-line strings
- Enhance readability
- Used for documentation
- Longer text such as instructions or error messages

Methods

Method = a function that is only available to a specific data type
str methods
- Standardizing input, or transforming text

# Calling a string method
string_variable.method()

Replacing parts of strings

.replace(text_to_be_replaced, text_to_change_it_to)

welcome_message = "Welcome to the recipe scaler, George"

welcome_message = welcome_message.replace("George", "John")

print(welcome_message)

Welcome to the recipe scaler, John

Changing case

Standardize user inputs like emails

ingredient_name = "Basil Leaves"

# Convert to lowercase
ingredient_name = ingredient_name.lower()
print(ingredient_name)

basil leaves

# Change to uppercase
ingredient_name = ingredient_name.upper()
print(ingredient_name)

BASIL LEAVES

Let's practice!

Introduction to Python for Developers