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Python Essentials for JS Developers

Barbara Streisand

Release： 2024-11-07 03:41:02

Original

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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"
```
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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)
```
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- Tuples (immutable lists):
```
   point = (10, 20)
```
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- Dictionaries (like JS objects):
```
   person = {"name": "Alice", "age": 30}
   person["name"]  # Accessing value
```
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- Sets (unique, unordered elements):
```
   unique_numbers = {1, 2, 3, 2}
```
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2. Control Structures

Conditionals:

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

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Loops:

For Loop (works with iterable objects):

   for num in [1, 2, 3]:
       print(num)

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While Loop:

   i = 0
   while i < 5:
       i += 1

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3. Functions

Function definition and return syntax:
```
 def greet(name):
     return f"Hello, {name}"
```
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Lambda Functions (like JS arrow functions):
```
 square = lambda x: x * x
```
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4. List Comprehensions and Generators

List Comprehensions (efficient way to create lists):
```
 squares = [x * x for x in range(10)]
```
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Generators (yielding values one by one):

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

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5. Error Handling

Try/Except Blocks:

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

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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"

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Inheritance:

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

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7. Common Built-In Functions

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

8. Working with Files

Reading and Writing:
```
 x = 10
 name = "Python"
```
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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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