Python Dictionaries Quiz
22 Questions
5 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What data type is a dictionary?

  • Mapping (correct)
  • String
  • Tuple
  • List

    • What is the purpose of a dictionary?

  • To perform mathematical calculations.
  • To store key-value pairs. (correct)
  • To represent a single piece of data.
  • To store ordered sequences of data.

    • What is the correct way to create an empty dictionary in Python?

  • ()
  • None
  • {} (correct)
  • []

    • Which of the following is NOT a valid key type for a Python dictionary?

    <p>List (C)</p> Signup and view all the answers

    What is the output of the following Python code?

    my_dict = {'apple': 1, 'banana': 2, 'cherry': 3}
print(my_dict['banana'])

    <p>2 (D)</p> Signup and view all the answers

    How do you remove a key-value pair from a dictionary?

    <p>Using the <code>del</code> statement. (B)</p> Signup and view all the answers

    Given a dictionary fruits = {'apple': 1, 'banana': 2}, what will be the number of items in the dictionary after executing the code fruits['pear'] = 3?

    <p>3 (A)</p> Signup and view all the answers

    What is a dictionary defined as in computer programming, specifically in Python?

    <p>A collection of key-value pairs that allows for storing and retrieving information using keys. (A)</p> Signup and view all the answers

    Which of the following statements about dictionaries is TRUE?

    <p>Dictionaries are mutable. (B)</p> Signup and view all the answers

    What type of data can be used as keys in a Python dictionary?

    <p>Any immutable data type. (D)</p> Signup and view all the answers

    How does a dictionary differ from a list in Python?

    <p>Dictionaries are unordered collections, while lists are ordered. (B)</p> Signup and view all the answers

    What is the advantage of using a dictionary over a list to store data associated with a person?

    <p>Dictionaries are more efficient for accessing specific information about a person using a key. (A)</p> Signup and view all the answers

    What kind of collection is a Python list?

    <p>Sequential (D)</p> Signup and view all the answers

    Which of these cannot be used as a key in a Python dictionary?

    <p>A list (B)</p> Signup and view all the answers

    What is the primary purpose of using the get() method when working with Python dictionaries?

    <p>To safely access the value associated with a key, allowing for a default return value if the key is not found. (D)</p> Signup and view all the answers

    Which of the following statements accurately describes the behavior of the update() method in Python dictionaries?

    <p>Modifies the existing dictionary by adding new key-value pairs and updating existing ones, without returning anything. (D)</p> Signup and view all the answers

    What is the primary difference between using the [] operator and the get() method to access values in a dictionary?

    <p>The <code>[]</code> operator raises a <code>KeyError</code> if the key is not found, while <code>get()</code> returns <code>None</code>. (C)</p> Signup and view all the answers

    Which of the following statements accurately describes the concept of aliasing in Python dictionaries?

    <p>Aliasing refers to having multiple references to the same dictionary object in memory. (C)</p> Signup and view all the answers

    What is the primary advantage of using tuples when looping through a dictionary?

    <p>Tuples provide a convenient way to access both the key and value simultaneously during iteration. (C)</p> Signup and view all the answers

    Which of the following statements accurately describes the use of the in and not in operators when working with dictionaries?

    <p>They are used to check if a specific key exists in the dictionary, returning <code>True</code> or <code>False</code> accordingly. (B)</p> Signup and view all the answers

    What is the primary purpose of using the update() method in Python dictionaries?

    <p>To add new key-value pairs to the dictionary and update existing ones, if necessary. (A)</p> Signup and view all the answers

    What is a key advantage of using dictionaries in Python compared to lists?

    <p>Dictionaries provide the ability to access elements using keys, enabling efficient and direct access to individual values. (D)</p> Signup and view all the answers

    Flashcards

    Tuple

    A collection to hold both key and value during loops.

    In operator

    Tests if a key exists in a dictionary.

    Get method

    Accesses value for a key without causing an error.

    None in Get method

    Returned when a key is not found using get().

    Signup and view all the flashcards

    Update method

    Updates dictionary with new key-value pairs or from another dict.

    Signup and view all the flashcards

    Parameters of Update

    Takes another dict or key-value pairs for updating.

    Signup and view all the flashcards

    Returning Value of Update

    Does not return a new dict; updates in place instead.

    Signup and view all the flashcards

    Aliasing

    When multiple references point to the same dictionary object.

    Signup and view all the flashcards

    Dictionary

    A collection of key-value pairs that maps keys to values.

    Signup and view all the flashcards

    Key

    A data item used to look up values in a dictionary.

    Signup and view all the flashcards

    Value

    The data item associated with a key in a dictionary.

    Signup and view all the flashcards

    Key-Value Pair

    A pair of items in a dictionary consisting of a key and its associated value.

    Signup and view all the flashcards

    Mapping Type

    A data type composed of collections of keys and values, like a dictionary.

    Signup and view all the flashcards

    Mutable vs Immutable

    Immutable types (like strings) can’t change, while mutable types can.

    Signup and view all the flashcards

    Nesting Dictionaries

    Placing dictionaries inside other dictionaries or lists.

    Signup and view all the flashcards

    Unordered Collection

    A type of collection where items have no specific order, like dictionaries.

    Signup and view all the flashcards

    Dictionary in Python

    A built-in mapping type that stores key-value pairs.

    Signup and view all the flashcards

    Creating an Empty Dictionary

    Start with {} to make a dictionary with no key-value pairs.

    Signup and view all the flashcards

    Adding Key-Value Pairs

    Use the assignment statement to insert key-value pairs into a dictionary.

    Signup and view all the flashcards

    Accessing Values

    Use keys to look up and retrieve values from a dictionary.

    Signup and view all the flashcards

    Deleting Key-Value Pairs

    Use the 'del' statement to remove an entry from a dictionary.

    Signup and view all the flashcards

    Dictionary Methods

    Built-in functions that perform operations on dictionaries, like len().

    Signup and view all the flashcards

    Study Notes

    Dictionaries Introduction

    • Dictionaries store related information; they connect pieces of information
    • Allow for modification of stored information
    • Can store a large amount of data
    • Can nest dictionaries inside lists, lists in dictionaries and vice versa.

    Understanding Dictionaries

    • Model real word objects accurately
    • Enables creating dictionaries representing people and storing various information (name, age, etc.)
    • Can store pairs of matched information (lists of words and their meanings)
    • Unlike lists, tuples or strings, dictionaries are not sequential collections.
    • Dictionaries use keys to access values (unorderly, associative collection)
    • Keys can be any immutable type (strings, numbers)
    • Values can be any Python data object

    Dictionary Glossary

    • Dictionary: A collection of key-value pairs mapping from keys to values; keys are immutable, values can be of any type.
    • Key: A data item mapped to a value in a dictionary. Used to look up values.

    Key-Value Pairs

    • Pairs of items in a dictionary
    • Values looked up by keys.

    Mapping Type

    • Contains keys and associated values
    • Python's built-in mapping type is the dictionary
    • Implements associative array abstract data type.

    Dictionaries

    • Different kind of collection
    • Python's built-in mapping type
    • Unordered, associative collection
    • Key can be any immutable type, value can be any Python data object

    Dictionary Operations

    • del statement: removes a key-value pair from a dictionary
    • Dictionaries are mutable (can be modified), can be changed by assigning values to keys

    Dictionary Methods

    • keys(): returns a view of dictionary's keys
    • values(): returns a view of dictionary's values
    • items(): returns a view of key-value pairs
    • get() returns the value associated with a key, or None if not found. (alternative return value available)
    • update(): adds elements form another dictionary to the dictionary, or updates the dictionary in place

    Aliasing & Copying Introduction

    • Aliasing: Multiple variables referencing the same dictionary object in memory. Modification in one variable affects all.

    • Copying: Creates a new, independent dictionary; original remains unchanged. Modifications to new copy do not change the original.

      • Shallow Copy: Creates new dictionary, values are still references to original. Modifying a nested object affects both copies.
      • Deep Copy: Creates a completely independent copy of the dictionary and its nested objects. Modifying nested objects does not affect the original.

    • Understanding these distinctions is important to avoid unwanted outcomes when modifying objects.

    Introduction to the join method

    • Joins an iterable of strings into a single string separated by a delimiter
    • Useful with lists of strings

    Join & Dictionaries

    • Dictionaries store key-value pairs
    • To use the join method on keys/values of a dictionary, the values must all be strings. Convert other types to strings if needed.

    Introduction to the split method

    • Splits a string into a list of substrings. Use a delimiter (optional); if no delimiter is supplied, whitespace is used by default.
    • Return Value: A list of strings

    Split & Dictionaries

    • Split strings into separate lists to use with dictionaries

    Filling a Dictionary with User Input

    • Use a while loop to repeatedly ask for user input
    • Store the responses in a dictionary, connect each response with a user (e.g. name;mountain to climb)

    Looping Through a Dictionary

    • Loop through key-value pairs, keys, or values
    • Accessing individual key-value pairs inside the loop to retrieve specific data.
    • Use descriptive variable names for keys and values

    Looping Through Keys in a Particular Order

    • Dictionary keys are stored in the same insertion order, though can be looped through in specific order using the sorted function.

    Looping Through Dictionary Values

    • Getting a list of values from a dictionary; set() is used to create unique items, useful when you need a list of things without repetition that might otherwise contain repeated items

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Python Dictionaries PDF

    Description

    Test your knowledge on Python dictionaries with this quiz! You'll answer questions about their purpose, usage, and the differences between dictionaries and lists. Perfect for anyone looking to reinforce their understanding of this essential data type in Python.

    More Like This

    Python Dictionaries Fundamentals
    10 questions

    Python Dictionaries Fundamentals

    NoteworthyEpitaph avatar
    NoteworthyEpitaph
    Dictionaries in Python
    18 questions

    Dictionaries in Python

    ElegantAtlanta avatar
    ElegantAtlanta
    Network Prog Ch 2: Python Data Types
    30 questions

    Network Prog Ch 2: Python Data Types

    Ameera avatar
    Ameera
    Python Dictionaries Quiz
    44 questions

    Python Dictionaries Quiz

    AmazingBiedermeier avatar
    AmazingBiedermeier
    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser