Python List Operations: Sorting, Traversing, Deleting, Adding, Modifying, Indexing, and Basic List Functions

1. Sorting

Shows case‑sensitive sorting, case‑insensitive sorting using key=str.lower , and reverse sorting with reverse=True .

fruits = ["banana", "Apple", "cherry", "orange"]
sorted_fruits = sorted(fruits)
print(sorted_fruits)  # ['Apple', 'banana', 'cherry', 'orange']

sorted_fruits = sorted(fruits, key=str.lower)
print(sorted_fruits)  # ['Apple', 'banana', 'cherry', 'orange']

sorted_fruits = sorted(fruits, key=str.lower, reverse=True)
print(sorted_fruits)  # ['orange', 'cherry', 'banana', 'Apple']

2. Traversing Lists

Demonstrates iteration using a for loop and a while loop.

fruits = ["banana", "Apple", "cherry", "orange"]
for fruit in fruits:
    print(fruit)

index = 0
while index < len(fruits):
    print(fruits[index])
    index += 1

3. Deleting List Items

Illustrates removal by value with remove() , deletion by index with del , and clearing the entire list with clear() .

fruits.remove("Apple")  # removes first matching element
print(fruits)  # ['banana', 'cherry', 'orange']

del fruits[1]  # deletes element at index 1
print(fruits)  # ['banana', 'cherry', 'orange']

fruits.clear()
print(fruits)  # []

4. Adding List Items

Shows how to append at the end, insert at a specific position, and extend with another list.

fruits.append("grape")
print(fruits)  # ['banana', 'Apple', 'cherry', 'orange', 'grape']

fruits.insert(1, "grape")
print(fruits)  # ['banana', 'grape', 'Apple', 'cherry', 'orange']

more_fruits = ["grape", "kiwi"]
fruits.extend(more_fruits)
print(fruits)  # ['banana', 'Apple', 'cherry', 'orange', 'grape', 'kiwi']

5. Modifying List Items

Provides examples of changing a single element, updating a slice, and inserting multiple elements via slice assignment.

fruits[1] = "apple"
print(fruits)  # ['banana', 'apple', 'cherry', 'orange']

fruits[1:3] = ["apple", "berry"]
print(fruits)  # ['banana', 'apple', 'berry', 'orange']

fruits[1:1] = ["apple", "berry"]
print(fruits)  # ['banana', 'apple', 'berry', 'Apple', 'cherry', 'orange']

6. Indexing and Slicing

Demonstrates normal indexing, negative indexing, slice ranges, negative slice ranges, and membership testing.

print(fruits[1])   # Apple
print(fruits[-1])  # orange
print(fruits[1:3])  # ['Apple', 'cherry']
print(fruits[-3:-1])  # ['Apple', 'cherry']
if "Apple" in fruits:
    print("Apple 存在于列表中")
else:
    print("Apple 不存在于列表中")

7. Basic List Operations

Creates a list, prints it, shows how to obtain its length, and demonstrates a mixed‑type list.

fruits = ["banana", "Apple", "cherry", "orange"]
print(fruits)  # ['banana', 'Apple', 'cherry', 'orange']
print(len(fruits))  # 4

mixed_list = [1, "banana", 3.14, True]
print(mixed_list)  # [1, 'banana', 3.14, True]