# Basic Commands
pip install package_name        # Install single package
pip install package_name==1.0.0 # Install specific version
pip uninstall package_name     # Remove package
pip list                       # List installed packages
pip freeze > requirements.txt  # Save package list
pip install -r requirements.txt # Install from requirements
pip show package_name         # Package info
pip search package_name       # Search PyPI
 
# Upgrade pip itself
python -m pip install --upgrade pip
 
# Install multiple packages
pip install requests pandas numpy
 
# Upgrade package
pip install --upgrade package_name
 
# Install in user directory
pip install --user package_name

# 1. Create virtual environment first
python -m venv myenv
 
# 2. Activate virtual environment
# Windows:
myenv\Scripts\activate
# Unix/macOS:
source myenv/bin/activate
 
# 3. Install packages
pip install -r requirements.txt
 
# 4. Save dependencies
pip freeze > requirements.txt

import os
 
# Current Working Directory
current = os.getcwd()
os.chdir('/path/to/dir')
 
# Path Operations
path = os.path.join('folder', 'subfolder', 'file.txt')
abs_path = os.path.abspath('file.txt')
dirname = os.path.dirname('/path/to/file.txt')
filename = os.path.basename('/path/to/file.txt')
 
# Directory Operations
os.mkdir('new_directory')         # Single directory
os.makedirs('path/to/directory')  # Recursive
os.rmdir('directory')            # Remove empty directory
os.removedirs('path/to/dir')     # Remove recursive
 
# File Operations
os.rename('old.txt', 'new.txt')
os.remove('file.txt')
exists = os.path.exists('file.txt')
 
# List Directory
files = os.listdir('.')
for root, dirs, files in os.walk('.'):
    print(root, dirs, files)
 
# Environment Variables
os.environ['MY_VAR'] = 'value'
value = os.environ.get('MY_VAR')
os.getenv('MY_VAR', 'default')
 
# System Commands
os.system('echo Hello')  # Execute system command
 
# Path Manipulation
os.path.split('/path/to/file.txt')
os.path.splitext('file.txt')

from datetime import datetime, date, time, timedelta
 
# Current Date and Time
now = datetime.now()      # Current local date and time
today = date.today()      # Current local date
utc_now = datetime.utcnow()  # Current UTC date and time
 
# Creating Date/Time
specific_date = date(2024, 2, 1)
specific_time = time(13, 30, 0)
specific_datetime = datetime(2024, 2, 1, 13, 30, 0)
 
# Formatting
formatted = now.strftime('%Y-%m-%d %H:%M:%S')
date_string = '2024-02-01 13:30:00'
parsed = datetime.strptime(date_string, '%Y-%m-%d %H:%M:%S')
 
# Date Operations
tomorrow = today + timedelta(days=1)
next_week = today + timedelta(weeks=1)
yesterday = today - timedelta(days=1)
 
# Time Differences
diff = datetime(2024, 12, 31) - datetime.now()
days_until = diff.days
seconds_until = diff.seconds
 
# Date Properties
print(now.year, now.month, now.day)
print(now.hour, now.minute, now.second)

import math
 
# Basic Math
print(math.sqrt(16))       # Square root: 4.0
print(math.pow(2, 3))      # Power: 8.0
print(math.fabs(-5))       # Absolute value: 5.0
print(math.factorial(5))    # Factorial: 120
 
# Rounding
print(math.floor(3.7))     # Floor: 3
print(math.ceil(3.2))      # Ceil: 4
print(math.trunc(3.7))     # Truncate: 3
 
# Constants
print(math.pi)             # Pi: 3.141592653589793
print(math.e)              # e: 2.718281828459045
print(math.tau)            # Tau: 6.283185307179586
 
# Trigonometry (radians)
print(math.sin(math.pi/2))  # Sine: 1.0
print(math.cos(math.pi))    # Cosine: -1.0
print(math.tan(math.pi/4))  # Tangent: 1.0
 
# Converting degrees/radians
print(math.degrees(math.pi)) # Radians to degrees: 180.0
print(math.radians(180))    # Degrees to radians: 3.141592653589793

import random
 
# Random Numbers
random_float = random.random()      # Float 0.0 <= x < 1.0
random_int = random.randint(1, 10)  # Integer between 1 and 10
random_range = random.randrange(0, 10, 2)  # Even numbers 0-8
 
# Floating point randomization
random_uniform = random.uniform(1.0, 10.0)  # Float between 1.0 and 10.0
 
# Sequence Operations
my_list = [1, 2, 3, 4, 5]
random.shuffle(my_list)             # Shuffle list in-place
random_choice = random.choice(my_list)  # Pick random item
random_samples = random.sample(my_list, 3)  # Pick 3 unique items
 
# Probability
weighted_choice = random.choices(['red', 'blue', 'green'],
                               weights=[5, 2, 3], k=2)  # Weighted random choices
 
# Seed for reproducibility
random.seed(42)  # Set seed for reproducible results

import json
 
# Python Object to JSON String
data = {
    'name': 'John',
    'age': 30,
    'city': 'New York',
    'hobbies': ['reading', 'music'],
    'active': True,
    'height': 1.75
}
 
# Serialization (Python to JSON)
json_string = json.dumps(data, indent=4, sort_keys=True)
print(json_string)
 
# Deserialization (JSON to Python)
python_dict = json.loads(json_string)
print(python_dict['name'])
 
# Working with Files
# Writing JSON to file
with open('data.json', 'w') as f:
    json.dump(data, f, indent=4)
 
# Reading JSON from file
with open('data.json', 'r') as f:
    loaded_data = json.load(f)
 
# Custom encoding/decoding
class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age
 
def person_encoder(obj):
    if isinstance(obj, Person):
        return {'name': obj.name, 'age': obj.age}
    raise TypeError(f'Object {obj} is not JSON serializable')
 
person = Person('John', 30)
json_string = json.dumps(person, default=person_encoder)

import sys
 
# System Information
print(sys.version)          # Python version
print(sys.platform)         # Operating system platform
print(sys.executable)       # Python executable location
 
# Python Path
print(sys.path)            # Module search path
sys.path.append('/path/to/module')  # Add path
 
# Standard Input/Output
sys.stdout.write('Hello\n')  # Write to stdout
sys.stderr.write('Error\n')  # Write to stderr
input_line = sys.stdin.readline()  # Read from stdin
 
# Command Line Arguments
print(sys.argv)            # List of command line arguments
script_name = sys.argv[0]  # Script name
arguments = sys.argv[1:]   # Arguments
 
# Exit Program
sys.exit(0)               # Exit with status 0 (success)
sys.exit(1)               # Exit with status 1 (error)
 
# Memory Information
print(sys.getsizeof([1, 2, 3]))  # Size of object in bytes
 
# Modules
print(sys.modules)        # Dictionary of loaded modules

from collections import Counter, defaultdict, namedtuple, deque, OrderedDict
 
# Counter
colors = ['red', 'blue', 'red', 'green', 'blue', 'blue']
color_count = Counter(colors)
print(color_count)                   # Counter({'blue': 3, 'red': 2, 'green': 1})
print(color_count.most_common(2))    # [('blue', 3), ('red', 2)]
 
# defaultdict
d = defaultdict(list)  # Default value is empty list
d['a'].append(1)      # No KeyError if key doesn't exist
d['b'].append(2)
print(d)              # defaultdict(<class 'list'>, {'a': [1], 'b': [2]})
 
# namedtuple
Point = namedtuple('Point', ['x', 'y'])
p = Point(11, y=22)
print(p.x, p.y)       # 11 22
print(p[0], p[1])     # 11 22
 
# deque (double-ended queue)
d = deque(['a', 'b', 'c'])
d.append('d')         # Add to right
d.appendleft('e')     # Add to left
print(d)              # deque(['e', 'a', 'b', 'c', 'd'])
 
# OrderedDict (ordered dictionary)
od = OrderedDict()
od['a'] = 1
od['b'] = 2
od['c'] = 3
print(od)             # OrderedDict([('a', 1), ('b', 2), ('c', 3)])