Python Collections: Lists, Tuples, Sets, and Dictionaries

Lists

A list is an ordered, mutable collection. Lists can contain any type of element and allow duplicates.

You can:

• Access elements by index: my_list[0]
• Append items: my_list.append("new")
• Insert at a position: my_list.insert(1, "inserted")
• Remove an item: my_list.remove("apple")
• Pop the last item: my_list.pop()
• Sort the list: my_list.sort()
• Join lists: list1 + list2 or list1.extend(list2)
• Nested lists: lists inside other lists for complex data

Tuples

A tuple is like a list, but it is immutable (cannot be changed).

You can:

• Access elements by index: my_tuple[0]
• Join tuples: new_tuple = t1 + t2
• Unpack tuples into variables: a, b = (1, 2)
• Check length: len(my_tuple)
• Count values: my_tuple.count(value)

Sets

A set is an unordered collection of unique elements.

You can:

• Add elements: my_set.add(x)
• Remove elements: my_set.remove(x) or discard(x)
• Check membership: x in my_set
• Set operations: union, intersection, difference, etc.

Dictionaries

A dictionary is a collection of key-value pairs. Keys must be unique.

You can:

• Access values: student["name"]
• Update values: student["age"] = 21
• Add key-value pairs: student["grade"] = "A"
• Remove pairs: student.pop("age")
• Loop through keys and values: for k, v in student.items()

Practice: Combine It All

Prompt: Create a program that stores a list of students. Each student is a dictionary with keys name and grades (a list). Then, print the average grade for each student.

Target Output:

Alice: 87.5
Bob: 91.5

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