✂️ Text Splitting & Joining — Break and Rebuild Strings

Learn to split strings into manageable pieces and join them back together efficiently.

🎯 The split() Method

Convert a single string into a list of substrings:

# Split by whitespace (default)
sentence = "Hello world from Python"
words = sentence.split()
print(words)  # ['Hello', 'world', 'from', 'Python']

# Split by specific delimiter
csv = "apple,banana,orange,grape"
fruits = csv.split(",")
print(fruits)  # ['apple', 'banana', 'orange', 'grape']

# Limit splits
text = "one-two-three-four"
result = text.split("-", 2)  # Split into max 3 parts
print(result)  # ['one', 'two', 'three-four']

💡 The join() Method

Combine list elements into a single string:

# Join with space
words = ["Hello", "beautiful", "world"]
sentence = " ".join(words)
print(sentence)  # Hello beautiful world

# Join with comma
items = ["apple", "banana", "orange"]
csv = ",".join(items)
print(csv)  # apple,banana,orange

# Join with empty string
chars = ["P", "y", "t", "h", "o", "n"]
word = "".join(chars)
print(word)  # Python

# Join with newline (multi-line output)
lines = ["First line", "Second line", "Third line"]
text = "\n".join(lines)
print(text)
# First line
# Second line
# Third line

🎨 splitlines() Method

Split by line breaks:

text = """First line
Second line
Third line"""

lines = text.splitlines()
print(lines)  # ['First line', 'Second line', 'Third line']

# Alternative: split by \n
lines = text.split("\n")
print(lines)  # Same result

📊 Split & Join Reference

💡 Practical Example: CSV Processing

# Parse CSV line
csv_line = "John,30,Engineer,New York"
fields = csv_line.split(",")
name, age, job, city = fields
print(f"{name} is a {job}")  # John is a Engineer

# Build CSV line
data = ["Alice", "28", "Designer", "Boston"]
csv_line = ",".join(data)
print(csv_line)  # Alice,28,Designer,Boston

# Process multiple lines
csv_data = """Name,Age,City
John,30,NYC
Jane,28,LA
Bob,35,Chicago"""

for line in csv_data.splitlines()[1:]:  # Skip header
    name, age, city = line.split(",")
    print(f"{name} is {age} years old")

🎯 URL Building & Parsing

# Build URL path
path_parts = ["api", "v1", "users", "123"]
url_path = "/" + "/".join(path_parts)
print(url_path)  # /api/v1/users/123

# Parse URL
url = "https://example.com/api/v1/users/123"
parts = url.split("/")
print(parts)  # ['https:', '', 'example.com', 'api', 'v1', 'users', '123']

# Extract specific parts
domain = parts[2]
endpoint = parts[3]
print(f"Domain: {domain}, Endpoint: {endpoint}")

🔑 Real-World Pattern: Parsing Configuration

# Parse config line
config_line = "database.host=localhost:5432"
key, value = config_line.split("=", 1)  # Split only on first =
print(f"Key: {key}, Value: {value}")
# Key: database.host, Value: localhost:5432

# Parse database URL
url = "user:password@localhost:5432"
credentials, location = url.split("@")
user, password = credentials.split(":")
host, port = location.split(":")
print(f"User: {user}, Host: {host}, Port: {port}")

🔑 Key Takeaways

🔗 What's Next?

Now apply all these skills to real-world string projects.

Ready to practice? Challenges | Quiz