Tuples and Dictionaries

Topics in this chapter

• Tuple Structure and Operations
• Tuple Mutability and Hashability
• Dictionary Construction and Updates
• Dictionary Access and Traversal
• Dictionary Semantics and Applications

Cheat sheet

Practice questions

1. Question 1Q-663C98

   Consider the following Python code: d = {"a": 1, "b": 2}; d["a"] = d["b"]. What will be the value of d after execution?

   1. A.{"a": 1, "b": 2}
   2. B.{"a": 2, "b": 2}
   3. C.{"a": 2, "b": 1}
   4. D.{"a": 1, "b": 1}
   See the answer and solution
2. Question 2Q-506693

   Explain why t = (1, 2, [3, 4]) allows t[2].append(5) but does not allow t[2] = [3, 4, 5].

   See the answer and solution
3. Question 3Q-0FB868

   What is printed by the following Python code? d = {"a": 10, "b": 20}; d["c"] = d.pop("a"); print(d["c"], len(d))

   1. A.10 2
   2. B.20 3
   3. C.10 3
   4. D.a 2
   See the answer and solution
4. Question 4Q-27EFC4

   Why can a tuple sometimes be used as a dictionary key while a list cannot? Give one valid tuple-key example and one invalid list-key example.

   See the answer and solution
5. Question 5Q-C01B21

   What is printed by the following Python code? t = (4, 7, 9, 7); print(t.index(7), t.count(7))

   1. A.0 2
   2. B.1 2
   3. C.1 1
   4. D.2 1
   See the answer and solution