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Python Essentials for JS Developers

1. Basic Syntax and Data Types

  • Variable Declaration: No need for var, let, or const. Just name the variable.

     x = 10
     name = "Python"
    
  • Primitive Types:

    • int (Integer)
    • float (Floating Point)
    • str (String)
    • bool (Boolean)
  • Data Structures:

    • Lists (like arrays in JS):
       numbers = [1, 2, 3]
       numbers.append(4)
    
    • Tuples (immutable lists):
       point = (10, 20)
    
    • Dictionaries (like JS objects):
       person = {"name": "Alice", "age": 30}
       person["name"]  # Accessing value
    
    • Sets (unique, unordered elements):
       unique_numbers = {1, 2, 3, 2}
    

2. Control Structures

  • Conditionals:

     if x > 5:
         print("Greater")
     elif x == 5:
         print("Equal")
     else:
         print("Lesser")
    
  • Loops:

    • For Loop (works with iterable objects):
       for num in [1, 2, 3]:
           print(num)
    
    • While Loop:
       i = 0
       while i < 5:
           i += 1
    

3. Functions

  • Function definition and return syntax:

     def greet(name):
         return f"Hello, {name}"
    
  • Lambda Functions (like JS arrow functions):

     square = lambda x: x * x
    

4. List Comprehensions and Generators

  • List Comprehensions (efficient way to create lists):

     squares = [x * x for x in range(10)]
    
  • Generators (yielding values one by one):

     def generate_numbers(n):
         for i in range(n):
             yield i
    

5. Error Handling

  • Try/Except Blocks:

     try:
         result = 10 / 0
     except ZeroDivisionError:
         print("Cannot divide by zero")
    

6. Classes and OOP

  • Class Definition:

     class Animal:
         def __init__(self, name):
             self.name = name
    
         def speak(self):
             return f"{self.name} makes a sound"
    
  • Inheritance:

     class Dog(Animal):
         def speak(self):
             return f"{self.name} barks"
    

7. Common Built-In Functions

  • len(), max(), min(), sum(), sorted()
  • Type conversions: int(), float(), str(), list(), dict()

8. Working with Files

  • Reading and Writing:

     with open("file.txt", "r") as file:
         data = file.read()
    

9. Important Libraries

  • NumPy for numerical operations, Pandas for data manipulation, and Matplotlib for plotting.

10. Differences from JavaScript

  • No need for semicolons.
  • Indentation is mandatory for defining blocks.
  • No switch statement (use if-elif instead).
  • None is used instead of null.

This summary should provide the essentials to begin coding in Python efficiently.

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