List Methods0%
List Methods
Beginner9 min read•Updated: 2026-09-03
List Methods
Python lists feature high-performance methods for ordering, searching, and duplicating data.
Key Concepts & Detailed Explanation
Key methods:
- .sort(key=None, reverse=False): Sorts list in-place (returns None).
- sorted(iterable): Returns a NEW sorted list without modifying original.
- .reverse(): Reverses elements in-place.
- .count(x): Returns number of times x appears.
- .index(x): Returns index of first occurrence of x.
- .copy(): Returns a shallow copy.
Code Examples & Output
Python
grades = [88, 92, 79, 95, 88, 100]
print("Count of 88:", grades.count(88)) # 2
print("First index of 95:", grades.index(95)) # 3
# Sorting in-place
grades.sort(reverse=True)
print("Sorted descending:", grades)
# Using sorted() to preserve original
original = [5, 2, 8, 1]
sorted_copy = sorted(original)
print("Original untouched:", original)
print("Sorted copy:", sorted_copy)
Expected Output:
Output
Count of 88: 2
First index of 95: 3
Sorted descending: [100, 95, 92, 88, 88, 79]
Original untouched: [5, 2, 8, 1]
Sorted copy: [1, 2, 5, 8]
Best Practices & Common Pitfalls
Remember that 'my_list.sort()' mutates in-place and returns None. Do not write 'sorted_list = my_list.sort()'.
Practice Quiz
1. What does the method 'my_list.sort()' return?
- A) The sorted list
- B) None
- C) True
- D) An iterator
Answer: B
Explanation: sort() operates in-place and returns None.
2. How do you create an independent shallow copy of a list 'lst'?
- A) lst.copy() or lst[:]
- B) new = lst
- C) clone(lst)
- D) lst.duplicate()
Answer: A
Explanation: lst.copy() or slicing lst[:] creates a shallow copy.
Practice Challenge
Sort a list of student names alphabetically in reverse order using the sort(reverse=True) method.
Next Lesson
Nested Lists
Continue learning with hands-on practice, examples, and exercises in the upcoming topic.
Related Lessons
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|---|---|
| Update Items | Nested Lists |
Practice Quiz
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