31_modules_tutorial.py

# Modules and Packages in Python

# ========== IMPORTING MODULES ==========

# 1. Importing entire module
import math
print(f"Pi: {math.pi}")
print(f"Square root: {math.sqrt(16)}")

# 2. Import with alias
import math as m
print(f"Cosine: {m.cos(0)}")

# 3. Import specific functions/objects
from math import pi, sqrt
print(f"Pi: {pi}")
print(f"Square root of 25: {sqrt(25)}")

# 4. Import everything (not recommended!)
# from math import *

# 5. Import with alias
from math import sqrt as square_root
print(square_root(9))

# ========== STANDARD MODULES ==========

# 6. os - operating system
import os
print(f"Current directory: {os.getcwd()}")

# 7. sys - system parameters
import sys
print(f"Python version: {sys.version}")
print(f"Platform: {sys.platform}")

# 8. random - random numbers
import random
print(f"Random number: {random.randint(1, 10)}")
print(f"Random choice: {random.choice(['a', 'b', 'c'])}")

# 9. datetime - working with dates
from datetime import datetime, timedelta
now = datetime.now()
print(f"Now: {now}")
tomorrow = now + timedelta(days=1)
print(f"Tomorrow: {tomorrow}")

# 10. collections - special collections
from collections import Counter, defaultdict, namedtuple

# Counter
words = ['apple', 'banana', 'apple', 'cherry', 'banana', 'apple']
count = Counter(words)
print(f"Counter: {count}")

# defaultdict
d = defaultdict(int)
d['key'] += 1
print(f"defaultdict: {d}")

# namedtuple
Point = namedtuple('Point', ['x', 'y'])
p = Point(10, 20)
print(f"Point: {p.x}, {p.y}")

# ========== CREATING YOUR OWN MODULES ==========

# 11. Create a file my_module.py:
# def greet(name):
#     return f"Hello, {name}!"
#
# PI = 3.14159

# Import it:
# import my_module
# print(my_module.greet("Pavel"))
# print(my_module.PI)

# ========== PACKAGES ==========

# 12. Package structure:
# my_package/
#     __init__.py
#     module1.py
#     module2.py
#     subpackage/
#         __init__.py
#         module3.py

# Import from package:
# from my_package import module1
# from my_package.subpackage import module3

# ========== __name__ and __main__ ==========

# 13. Check if module is run directly
if __name__ == "__main__":
    print("Module is run directly")
else:
    print("Module is imported")

# ========== INSTALLING PACKAGES ==========

# 14. pip - package manager
# pip install requests
# pip install numpy
# pip list
# pip uninstall package_name

# ========== VIRTUAL ENVIRONMENTS ==========

# 15. Creating a virtual environment
# python -m venv myenv

# Activation:
# Windows: myenv\\Scripts\\activate
# Linux/Mac: source myenv/bin/activate

# Deactivation:
# deactivate

# ========== USEFUL MODULES ==========

# json - working with JSON
import json
data = {"name": "Pavel", "age": 25}
json_string = json.dumps(data)
print(f"JSON: {json_string}")

# re - regular expressions
import re
pattern = r'\d+'
text = "I have 5 apples and 10 bananas"
numbers = re.findall(pattern, text)
print(f"Numbers: {numbers}")

# pathlib - working with paths
from pathlib import Path
path = Path('..')
print(f"Files: {list(path.glob('*.py'))}")