Python List Methods

Lists are used constantly, so you should master their methods and know what each method does.

  A common beginner mistake:
  Some list methods modify the list and return nothing (`None`). That is normal.
  
  ## Adding items
  
  ```python
  fruits = ["apple", "banana"]
  
  fruits.append("orange")
  print(fruits)
  
  fruits.insert(1, "grape")
  print(fruits)
  
  fruits.extend(["mango", "kiwi"])
  print(fruits)
  ```
  
  Expected output:
  
  ```
  ['apple', 'banana', 'orange']
  ['apple', 'grape', 'banana', 'orange']
  ['apple', 'grape', 'banana', 'orange', 'mango', 'kiwi']
  ```
  
  ## Removing items
  
  ```python
  fruits = ["apple", "banana", "orange", "banana"]
  
  fruits.remove("banana")  # removes first banana
  print(fruits)
  
  removed = fruits.pop(1)  # removes by index and returns it
  print("Removed:", removed)
  print("Now:", fruits)
  
  fruits.clear()
  print(fruits)
  ```
  
  Expected output:
  
  ```
  ['apple', 'orange', 'banana']
  Removed: orange
  Now: ['apple', 'banana']
  []
  ```
  
  ## Sorting and reversing
  
  ```python
  numbers = [5, 2, 8, 1, 9]
  
  numbers.sort()
  print(numbers)
  
  numbers.sort(reverse=True)
  print(numbers)
  
  numbers.reverse()
  print(numbers)
  ```
  
  Expected output:
  
  ```
  [1, 2, 5, 8, 9]
  [9, 8, 5, 2, 1]
  [1, 2, 5, 8, 9]
  ```
  
  ## Searching
  
  ```python
  cities = ["Miami", "Austin", "Denver", "Boston"]
  print(cities.index("Denver"))
  
  nums = [1, 2, 3, 2, 2]
  print(nums.count(2))
  
  print("Miami" in cities)
  ```
  
  Expected output:
  
  ```
  2
  3
  True
  ```
  
  ## Copy list safely
  
  ```python
  original = [1, 2, 3]
  copy1 = original.copy()
  
  copy1.append(4)
  print("Original:", original)
  print("Copy:", copy1)
  ```
  
  Expected output:
  
  ```
  Original: [1, 2, 3]
  Copy: [1, 2, 3, 4]
  ```
  
  ## Graph: list method categories
  
  ```mermaid
  flowchart LR
    A[List] --> B[Add: append/extend/insert]
    A --> C[Remove: remove/pop/clear]
    A --> D[Order: sort/reverse]
    A --> E[Search: index/count/in]
    A --> F[Copy: copy/slicing]
  ```
  
  In the next lesson, you will master string methods with the same mindset: what each method returns and how to use them in real programs.