Quick Start

age = 25
price = 19.99
complex_num = 3 + 4j
 
name = "Alice"
message = 'Hello, World!'
multiline = """This is
a multiline string"""
 
is_active = True
is_complete = False
 
result = None
 
print(type(age))        # <class 'int'>
print(type(price))      # <class 'float'>
print(type(name))       # <class 'str'>
print(type(is_active))  # <class 'bool'>
 
num_str = "42"
num = int(num_str)      # Convert string to int
print(num + 8)          # 50
 
float_str = str(3.14)   # Convert float to string
print(float_str)        # "3.14"

score = 85
 
if score >= 90:
    print("Grade: A")
elif score >= 80:
    print("Grade: B")
elif score >= 70:
    print("Grade: C")
else:
    print("Grade: F")
 
fruits = ["apple", "banana", "cherry"]
for fruit in fruits:
    print(f"I like {fruit}")
 
for i in range(5):
    print(i)  # 0, 1, 2, 3, 4
 
count = 0
while count < 3:
    print(f"Count: {count}")
    count += 1
 
for num in range(10):
    if num == 3:
        continue  # Skip 3
    if num == 7:
        break     # Stop at 7
    print(num)    # 0, 1, 2, 4, 5, 6

def greet(name):
    return f"Hello, {name}!"
 
message = greet("Alice")
print(message)  # Hello, Alice!
 
def add(a, b):
    return a + b
 
result = add(5, 3)
print(result)   # 8
 
def greet_with_title(name, title="Mr."):
    return f"Hello, {title} {name}"
 
print(greet_with_title("Smith"))          # Hello, Mr. Smith
print(greet_with_title("Johnson", "Dr.")) # Hello, Dr. Johnson
 
def get_min_max(numbers):
    return min(numbers), max(numbers)
 
minimum, maximum = get_min_max([3, 7, 1, 9, 4])
print(f"Min: {minimum}, Max: {maximum}")  # Min: 1, Max: 9
 
def sum_all(*args):
    return sum(args)
 
print(sum_all(1, 2, 3, 4, 5))  # 15
 
def display_info(**kwargs):
    for key, value in kwargs.items():
        print(f"{key}: {value}")
 
display_info(name="Alice", age=30, city="NYC")

fruits = ["apple", "banana", "cherry"]
fruits.append("date")
fruits[1] = "blueberry"
print(fruits)  # ['apple', 'blueberry', 'cherry', 'date']
 
person = {
    "name": "Alice",
    "age": 30,
    "city": "NYC"
}
print(person["name"])   # Alice
person["email"] = "alice@example.com"
print(person.keys())    # dict_keys(['name', 'age', 'city', 'email'])
print(person.values())  # dict_values(['Alice', 30, 'NYC', 'alice@example.com'])
 
coordinates = (10, 20)
x, y = coordinates  # Unpacking
print(f"x={x}, y={y}")  # x=10, y=20
 
numbers = {1, 2, 3, 2, 1}
print(numbers)  # {1, 2, 3} (duplicates removed)
numbers.add(4)
print(numbers)  # {1, 2, 3, 4}
 
my_list = [1, 2, 3, 4, 5]
print(len(my_list))     # 5
print(3 in my_list)     # True
print(my_list[0])       # 1 (first element)
print(my_list[-1])      # 5 (last element)
print(my_list[1:3])     # [2, 3] (slicing)

text = "  Hello, World!  "
print(text.strip())           # "Hello, World!" (remove whitespace)
print(text.lower())           # "  hello, world!  "
print(text.upper())           # "  HELLO, WORLD!  "
print(text.replace("World", "Python"))  # "  Hello, Python!  "
 
sentence = "Python is amazing"
words = sentence.split()      # ['Python', 'is', 'amazing']
joined = "-".join(words)      # "Python-is-amazing"
print(joined)
 
text = "Python"
print(text[0])      # P
print(text[-1])     # n
print(text[0:3])    # Pyt
print(text[2:])     # thon
print(text[:4])     # Pyth
 
name = "Alice"
age = 30
 
message = f"My name is {name} and I am {age} years old"
print(message)  # My name is Alice and I am 30 years old
 
message = "My name is {} and I am {} years old".format(name, age)
print(message)
 
email = "alice@example.com"
print(email.startswith("alice"))  # True
print(email.endswith(".com"))     # True
print("@" in email)               # True

with open("data.txt", "w") as file:
    file.write("Hello, File!\n")
    file.write("This is line 2\n")
    file.write("This is line 3\n")
 
with open("data.txt", "r") as file:
    content = file.read()
    print(content)
 
with open("data.txt", "r") as file:
    for line in file:
        print(line.strip())  # strip() removes newline
 
with open("data.txt", "r") as file:
    lines = file.readlines()
    print(lines)  # ['Hello, File!\n', 'This is line 2\n', ...]
 
with open("data.txt", "a") as file:
    file.write("Appended line\n")
 
import json
 
data = {"name": "Alice", "age": 30, "city": "NYC"}
with open("data.json", "w") as file:
    json.dump(data, file, indent=2)
 
with open("data.json", "r") as file:
    loaded_data = json.load(file)
    print(loaded_data["name"])  # Alice

try:
    result = 10 / 0
except ZeroDivisionError:
    print("Cannot divide by zero!")
 
try:
    num = int("not a number")
except ValueError:
    print("Invalid number format")
except ZeroDivisionError:
    print("Cannot divide by zero")
 
try:
    risky_operation()
except Exception as e:
    print(f"An error occurred: {e}")
 
try:
    file = open("data.txt", "r")
    content = file.read()
except FileNotFoundError:
    print("File not found!")
else:
    print("File read successfully")
    print(content)
finally:
    print("This always executes")
 
def validate_age(age):
    if age < 0:
        raise ValueError("Age cannot be negative")
    if age > 150:
        raise ValueError("Age seems unrealistic")
    return age
 
try:
    validate_age(-5)
except ValueError as e:
    print(f"Validation error: {e}")

numbers = [1, 2, 3, 4, 5]
squares = [n ** 2 for n in numbers]
print(squares)  # [1, 4, 9, 16, 25]
 
evens = [n for n in numbers if n % 2 == 0]
print(evens)  # [2, 4]
 
words = ["hello", "world", "python"]
uppercase = [word.upper() for word in words]
print(uppercase)  # ['HELLO', 'WORLD', 'PYTHON']
 
matrix = [[i * j for j in range(1, 4)] for i in range(1, 4)]
print(matrix)
 
numbers = [1, 2, 3, 4, 5]
squares_dict = {n: n ** 2 for n in numbers}
print(squares_dict)  # {1: 1, 2: 4, 3: 9, 4: 16, 5: 25}
 
numbers = [1, 2, 2, 3, 3, 3, 4]
unique_squares = {n ** 2 for n in numbers}
print(unique_squares)  # {1, 4, 9, 16}
 
large_numbers = (n ** 2 for n in range(1000000))
print(next(large_numbers))  # 0
print(next(large_numbers))  # 1

class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age
 
    def greet(self):
        return f"Hello, my name is {self.name}"
 
    def is_adult(self):
        return self.age >= 18
 
alice = Person("Alice", 30)
bob = Person("Bob", 15)
 
print(alice.greet())        # Hello, my name is Alice
print(alice.is_adult())     # True
print(bob.is_adult())       # False
 
class Student(Person):
    def __init__(self, name, age, student_id):
        super().__init__(name, age)
        self.student_id = student_id
 
    def get_id(self):
        return self.student_id
 
student = Student("Charlie", 20, "S12345")
print(student.greet())      # Hello, my name is Charlie
print(student.get_id())     # S12345
 
class Circle:
    def __init__(self, radius):
        self._radius = radius
 
    @property
    def radius(self):
        return self._radius
 
    @radius.setter
    def radius(self, value):
        if value < 0:
            raise ValueError("Radius must be positive")
        self._radius = value
 
    @property
    def area(self):
        return 3.14159 * self._radius ** 2
 
circle = Circle(5)
print(circle.area)      # 78.53975
circle.radius = 10
print(circle.area)      # 314.159

import math
print(math.pi)          # 3.141592653589793
print(math.sqrt(16))    # 4.0
 
from math import pi, sqrt
print(pi)               # 3.141592653589793
print(sqrt(25))         # 5.0
 
import datetime as dt
now = dt.datetime.now()
print(now)
 
from collections import Counter, defaultdict
 
words = ["apple", "banana", "apple", "cherry", "banana", "apple"]
count = Counter(words)
print(count)            # Counter({'apple': 3, 'banana': 2, 'cherry': 1})
print(count["apple"])   # 3
 
import os
import sys
import random
import json
 
print(random.randint(1, 10))     # Random integer between 1 and 10
print(random.choice(['a', 'b', 'c']))  # Random choice
 
print(os.getcwd())      # Current working directory
print(os.listdir('.'))  # List files in current directory
 
 

square = lambda x: x ** 2
print(square(5))  # 25
 
add = lambda a, b: a + b
print(add(3, 7))  # 10
 
numbers = [1, 2, 3, 4, 5]
squared = list(map(lambda x: x ** 2, numbers))
print(squared)  # [1, 4, 9, 16, 25]
 
evens = list(filter(lambda x: x % 2 == 0, numbers))
print(evens)  # [2, 4]
 
people = [
    {"name": "Alice", "age": 30},
    {"name": "Bob", "age": 25},
    {"name": "Charlie", "age": 35}
]
sorted_people = sorted(people, key=lambda p: p["age"])
print([p["name"] for p in sorted_people])  # ['Bob', 'Alice', 'Charlie']
 
operations = [lambda x: x + 1, lambda x: x * 2, lambda x: x ** 2]
result = [op(5) for op in operations]
print(result)  # [6, 10, 25]

python -m venv myenv
 
source myenv/bin/activate
myenv\Scripts\activate
 
pip install requests
 
pip install requests==2.28.0
 
pip install requests numpy pandas
 
pip list
 
pip freeze > requirements.txt
 
pip install -r requirements.txt
 
deactivate

import requests
 
response = requests.get("https://api.github.com")
print(response.status_code)  # 200
data = response.json()
print(data.keys())
 
import pandas as pd
 
data = {
    "name": ["Alice", "Bob", "Charlie"],
    "age": [30, 25, 35],
    "city": ["NYC", "LA", "Chicago"]
}
df = pd.DataFrame(data)
print(df)
 
print(df["age"].mean())  # 30.0

x = 10
name = "Alice"
 
def greet(name):
    return f"Hello, {name}!"
 
class Person:
    def __init__(self, name):
        self.name = name
 
my_list = [1, 2, 3]
my_dict = {"key": "value"}
 
if condition:
    do_something()
for item in items:
    process(item)
 
try:
    risky_operation()
except Exception as e:
    handle_error(e)
 
squares = [x**2 for x in range(10)]
 
import math
from collections import Counter

x = 42              # int
y = 3.14            # float
name = "Alice"      # str
is_valid = True     # bool
 
fruits = ["apple", "banana", "cherry"]
fruits.append("date")
fruits[0]           # First element
fruits[-1]          # Last element
 
person = {"name": "Alice", "age": 30}
person["name"]      # Access value
person["email"] = "alice@example.com"  # Add key
 
def add(a, b):
    return a + b
 
class Dog:
    def __init__(self, name):
        self.name = name
 
    def bark(self):
        return f"{self.name} says woof!"
 
if x > 0:
    print("Positive")
elif x < 0:
    print("Negative")
else:
    print("Zero")
 
for i in range(5):
    print(i)
 
for item in items:
    print(item)
 
squares = [x**2 for x in range(10)]
evens = [x for x in range(10) if x % 2 == 0]
 
with open("file.txt", "r") as f:
    content = f.read()
 
try:
    risky_operation()
except ValueError as e:
    print(f"Error: {e}")

len([1, 2, 3])          # 3
sum([1, 2, 3])          # 6
max([1, 2, 3])          # 3
min([1, 2, 3])          # 1
sorted([3, 1, 2])       # [1, 2, 3]
reversed([1, 2, 3])     # [3, 2, 1]
enumerate(["a", "b"])   # [(0, 'a'), (1, 'b')]
zip([1, 2], [3, 4])     # [(1, 3), (2, 4)]
range(5)                # 0, 1, 2, 3, 4
type(x)                 # Get type
isinstance(x, int)      # Check type