Python Data Structures
Lists, dictionaries, sets, tuples, list comprehensions, generators, itertools
1What is the fundamental difference between a list and a tuple in Python?
What is the fundamental difference between a list and a tuple in Python?
Answer
Lists are mutable (can be modified after creation) while tuples are immutable (cannot be modified). This immutability makes tuples hashable and usable as dictionary keys, unlike lists. Tuples are also slightly more performant in terms of memory usage and access speed.
2Which method should be used to add an element at the end of a Python list?
Which method should be used to add an element at the end of a Python list?
Answer
The append() method adds a single element at the end of a list. It modifies the list in place and returns None. To add multiple elements, use extend() or the += operator. The insert() method allows adding at a specific position.
3How to create an empty dictionary in Python?
How to create an empty dictionary in Python?
Answer
An empty dictionary can be created with {} or dict(). The {} syntax is more concise and slightly faster. The {} notation creates an empty dictionary, while set() creates an empty set. For an empty set, you must use set() because {} is reserved for dictionaries.
What is the result of the expression [x**2 for x in range(5)]?
What characteristic distinguishes a set from other Python collections?
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