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.

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