Practice Questions: Python 3 Data Collections

Data Structures Practice Questions

Practice Questions - Python 3 Data Collections

This practice guide is structured to reinforce the data collections concepts covered in Step 1: Data Structures Guide. Solving these exercises will help you develop collection indexing, mutable state adjustments, key-value mapping, set algebra logic, and string parsing skills.

Guidelines for Effective Learning:

Solve Individually First: Attempt to write or trace out the logic for each task before reviewing the provided answers.
Execute Locally: Run these blocks in your local terminal. Changing variables and monitoring the outputs is essential for programming mastery.
Trace Complex Nested Structures: For dictionary-in-dictionary or list-in-list questions, map the outer index first before drilling down to inner elements.

Practice Questions Index

Section 1: Lists (Questions 1-10) — Indexing, mutability, append/insert/pop, and slicing.
Section 2: Tuples (Questions 11-20) — Unpacking, constant coordination, and immutability logic.
Section 3: Sets (Questions 21-30) — Deduplication, membership checking, and set mathematics.
Section 4: Dictionaries (Questions 31-40) — Key-value associations, safe retrieves, nested databases, and looping.
Section 5: Strings (Questions 41-50) — Character sequences, formatting, case manipulations, and parsing.

1. Lists: Ordered Collections (Questions 1-10)

Question 1: Index-Based Access

Task: Create a list named schedule containing five core subjects. Print the first, third, and fifth elements using index markers.

Answer:


main.pyRunnable
schedule = ["Physics", "English Lit", "Calculus", "World History", "Chemistry"]

print("Period 1:", schedule[0])
print("Period 3:", schedule[2])
print("Period 5:", schedule[4])

Question 2: Modifying List State

Task: Take the list schedule from Question 1. Append the string "Physical Education" to the end, insert "Computer Science" at index 1, and remove the subject "Chemistry". Print the updated list.

Answer:


main.pyRunnable
schedule = ["Physics", "English Lit", "Calculus", "World History", "Chemistry"]

schedule.append("Physical Education")    # Adds to end
schedule.insert(1, "Computer Science")   # Inserts at index 1
schedule.remove("Chemistry")            # Removes first instance

print("Updated Schedule:", schedule)

Question 3: Extracting Sub-Sequences (Slicing)

Task: Extract a sub-sequence list of the first three items and another sub-sequence containing the remaining items from the following schedule:


main.pyRunnable
schedule = ["Physics", "Computer Science", "English Lit", "Calculus", "World History", "Physical Education"]

Answer:


main.pyRunnable
schedule = ["Physics", "Computer Science", "English Lit", "Calculus", "World History", "Physical Education"]

morning_courses = schedule[:3]
afternoon_courses = schedule[3:]

print("Morning Courses:", morning_courses)
print("Afternoon Courses:", afternoon_courses)

Question 4: Searching and Counting Occurrences

Task: Retrieve the index location of "Calculus" from a schedule list, and count how many times "Study Hall" appears in the collection.

Answer:


main.pyRunnable
schedule = ["Physics", "Study Hall", "Calculus", "World History", "Study Hall"]

calculus_index = schedule.index("Calculus")
study_hall_count = schedule.count("Study Hall")

print("Calculus Index Position:", calculus_index)
print("Study Hall Frequency:", study_hall_count)

Question 5: Numeric Array Sorting

Task: Sort a list of raw numeric test scores in ascending order, and then in descending order.

Answer:


main.pyRunnable
test_scores = [85, 92, 78, 96, 88]

## Ascending sort
test_scores.sort()
print("Ascending Sort:", test_scores)

## Descending sort
test_scores.sort(reverse=True)
print("Descending Sort:", test_scores)

Question 6: Merging and Replicating Lists

Task: Combine two lists, core_courses and elective_courses. Then, replicate a two-element task list chores three times in sequence.

Answer:


main.pyRunnable
core_courses = ["Physics", "Calculus"]
elective_courses = ["Art", "Music"]

combined_list = core_courses + elective_courses
print("Merged Courses List:", combined_list)

chores = ["Clean Desk", "Backup Server"]
repeated_tasks = chores * 3
print("Replicated Task List:", repeated_tasks)

Question 7: Conditional List Extraction

Task: Given a list of numerical student scores, extract only those scores that are greater than or equal to 75 into a new list.

Answer:


main.pyRunnable
all_scores = [65, 88, 72, 95, 54, 82]

passing_scores = [score for score in all_scores if score >= 75]
print("Passing Scores Array:", passing_scores)

Question 8: Accessing Nested Matrices (Grids)

Task: Retrieve the value sitting at Row 2, Column 3 from the following seated student matrix (zero-indexed):


main.pyRunnable
classroom_grid = [
    ["Alice", "Bob", "Charlie"],  # Row 1 (index 0)
    ["David", "Emma", "Frank"],    # Row 2 (index 1)
    ["Grace", "Henry", "Ivy"]     # Row 3 (index 2)
]

Answer:


main.pyRunnable
classroom_grid = [
    ["Alice", "Bob", "Charlie"],
    ["David", "Emma", "Frank"],
    ["Grace", "Henry", "Ivy"]
]

## Row 2 is index 1, Column 3 is index 2
occupant = classroom_grid[1][2]
print("Seated at Row 2, Seat 3:", occupant)

Question 9: List Statistics Calculations

Task: Compute the maximum, minimum, and average values from a list of numerical scores.

Answer:


main.pyRunnable
scores = [85, 92, 78, 96, 88]

highest_score = max(scores)
lowest_score = min(scores)
average_score = sum(scores) / len(scores)

print(f"Max: {highest_score} | Min: {lowest_score} | Average: {average_score:.1f}")

Question 10: Dynamic Sequence Shifts

Task: Extract the last element of a list using pop() and insert it at the very beginning of the list (index 0).

Answer:


main.pyRunnable
courses = ["Physics", "English Lit", "Calculus", "World History", "Art"]

last_element = courses.pop()  # Removes and returns "Art"
courses.insert(0, last_element)

print("Shifted Sequence:", courses)

Section Checkup

Check to complete: I can declare lists, modify elements by index, and execute append/insert/pop operations. (Click to check)
Check to complete: I understand how to use index markers and step steps to slice sub-lists. (Click to check)

2. Tuples: Fixed Records (Questions 11-20)

Question 11: Tuple Declaration and Access

Task: Create a tuple holding three constant integers representing a locker combination. Print the second integer.

Answer:


main.pyRunnable
combination = (42, 17, 8)

print("Locker Combination Step 2:", combination[1])

Question 12: Immutability Resolution

Task: Explain what error is raised if you attempt to reassign student_record[1] = 4.0 in the following tuple, and write code that successfully creates a new tuple reflecting that update:


main.pyRunnable
student_record = ("Alice Smith", 3.8)

Answer: Attempting to assign values directly to an index of a declared tuple raises a TypeError: 'tuple' object does not support item assignment. To resolve this, you must declare a new tuple combining the original name and the new GPA value:


main.pyRunnable
student_record = ("Alice Smith", 3.8)

## Reconstruct a new tuple instead of modifying the old one
updated_record = (student_record[0], 4.0)
print("Updated Record Tuple:", updated_record)

Question 13: Unpacking Variables

Task: Unpack a three-element tuple storing demographic coordinates (Latitude, Longitude, and Altitude) into three distinct variables and print them.

Answer:


main.pyRunnable
coordinates = (37.7749, -122.4194, 25.5)

latitude, longitude, altitude = coordinates

print("Latitude:", latitude)
print("Longitude:", longitude)
print("Altitude:", altitude)

Question 14: Merging Constant Records

Task: Merge a student's basic registration profile tuple and their academic statistics tuple using concatenation.

Answer:


main.pyRunnable
profile = ("Vance", 16)
stats = ("Grade 10", 3.90)

full_profile = profile + stats
print("Merged Profile Tuple:", full_profile)

Question 15: Single-Element Tuple Validation

Task: Write code showing the difference in data types between a parenthesized integer (2026) and a single-element tuple containing 2026.

Answer:


main.pyRunnable
## Parenthesized expression with no comma compiles as an integer
integer_value = (2026)
print("Type without comma:", type(integer_value))  # Outputs: <class 'int'>

## Adding a trailing comma makes it a tuple
tuple_value = (2026,)
print("Type with comma:", type(tuple_value))        # Outputs: <class 'tuple'>

Question 16: Index and Count Checks

Task: Count the occurrences of "A" in a tuple of letter grades, and find the index location of the first "B" grade.

Answer:


main.pyRunnable
grades = ("A", "B", "A", "C", "A")

a_frequency = grades.count("A")
first_b_index = grades.index("B")

print("Frequency of A:", a_frequency)
print("Index of First B:", first_b_index)

Question 17: Sorting Immutable Structures

Task: Sort the numeric elements of a tuple by converting it to a list, executing a sort, and converting it back.

Answer:


main.pyRunnable
raw_tuple = (88, 95, 74, 91)

temp_list = list(raw_tuple)
temp_list.sort()
sorted_tuple = tuple(temp_list)

print("Sorted Tuple:", sorted_tuple)

Question 18: Constant Tuple Keys

Task: Retrieve a value from a dictionary that uses coordinate tuples as keys representing physical rows and columns.

Answer:


main.pyRunnable
grid_assignments = {
    (1, 1): "ServerA",
    (1, 2): "ServerB",
    (2, 1): "ServerC"
}

## Retrieve target occupying value at Row 1, Column 2
active_node = grid_assignments[(1, 2)]
print("Occupant at (1,2):", active_node)

Question 19: Membership Checks

Task: Verify if the subject "Chemistry" is present inside a tuple of curriculum requirements using the in operator.

Answer:


main.pyRunnable
requirements = ("Algebra", "English Lit", "US History", "Chemistry")

is_present = "Chemistry" in requirements
print("Chemistry requirement exists:", is_present)

Question 20: Multidimensional Records

Task: Extract and print the grade value of the second student in the following nested tuple array:


main.pyRunnable
gradebook = (
    ("Alice", 95.0),
    ("Bob", 88.5),
    ("Charlie", 92.0)
)

Answer:


main.pyRunnable
gradebook = (
    ("Alice", 95.0),
    ("Bob", 88.5),
    ("Charlie", 92.0)
)

bob_grade = gradebook[1][1]
print("Bob's Grade:", bob_grade)

Section Checkup

Check to complete: I can create, access, and unpack Tuples. (Click to check)
Check to complete: I understand that tuples are immutable and know how to sort them using list conversions. (Click to check)

3. Sets: Unique Elements (Questions 21-30)

Question 21: Set Initialization

Task: Initialize a set storing unique club members. Demonstrate how duplicate elements passed during initialization are automatically filtered.

Answer:


main.pyRunnable
chess_club = {"Alice", "Bob", "Alice", "Charlie"}

## Duplicate "Alice" is automatically filtered
print("Unique Chess Club Set:", chess_club)

Question 22: Deduplicating Lists

Task: Take a list containing duplicate email strings and convert it to a Set to filter out all duplicates.

Answer:


main.pyRunnable
raw_emails = ["admin@school.edu", "user@school.edu", "admin@school.edu"]

unique_emails = set(raw_emails)
print("Deduplicated Emails Set:", unique_emails)

Question 23: Set Modifiers

Task: Add "David" to an active club set, and safely discard "Carol" without raising an error if she is not present in the set.

Answer:


main.pyRunnable
drama_club = {"Alice", "Bob", "Carol"}

drama_club.add("David")
drama_club.discard("Carol")  # discard does not raise error if element is missing

print("Updated Drama Club Set:", drama_club)

Question 24: Common Elements (Intersection)

Task: Find the elements that exist in both a science club set and an art club set.

Answer:


main.pyRunnable
science = {"Alice", "Bob", "Charlie"}
art = {"Bob", "David", "Emma"}

common_students = science.intersection(art)  # Or: science & art
print("Students in both clubs:", common_students)

Question 25: All Unique Elements (Union)

Task: Combine two club sets to find all unique students participating in at least one activity.

Answer:


main.pyRunnable
science = {"Alice", "Bob", "Charlie"}
art = {"Bob", "David", "Emma"}

total_participants = science.union(art)  # Or: science | art
print("Unique participating students:", total_participants)

Question 26: Set Deductions (Difference)

Task: Find all students who are in the science club but are NOT in the art club.

Answer:


main.pyRunnable
science = {"Alice", "Bob", "Charlie"}
art = {"Bob", "David", "Emma"}

science_only = science.difference(art)  # Or: science - art
print("Science Club only:", science_only)

Question 27: Symmetric Difference

Task: Find all students who participate in exactly one club (excluding those who are in both).

Answer:


main.pyRunnable
science = {"Alice", "Bob", "Charlie"}
art = {"Bob", "David", "Emma"}

exclusive_students = science.symmetric_difference(art)  # Or: science ^ art
print("Students in exactly one club:", exclusive_students)

Question 28: Subsets and Supersets

Task: Check if a set of honors students is a subset of all registered students.

Answer:


main.pyRunnable
registered_students = {"Alice", "Bob", "Charlie", "David", "Emma"}
honors_students = {"Alice", "Charlie"}

is_subset = honors_students.issubset(registered_students)
print("Honors subset of Registered:", is_subset)

Question 29: Disjoint Allocations

Task: Check if two sets, biology_class and geology_class, have completely zero overlapping elements (disjoint).

Answer:


main.pyRunnable
biology_class = {"Alice", "Bob"}
geology_class = {"David", "Emma"}

no_overlap = biology_class.isdisjoint(geology_class)
print("Classes have zero overlapping students:", no_overlap)

Question 30: High-Speed Membership Testing

Task: Demonstrate a fast membership verification check on a set of allowed IP addresses.

Answer:


main.pyRunnable
allowed_ips = {"192.168.1.1", "10.0.0.5", "172.16.2.20"}

is_allowed = "192.168.1.1" in allowed_ips
print("IP address verified:", is_allowed)

Section Checkup

Check to complete: I can deduplicate lists by converting them to Sets. (Click to check)
Check to complete: I can execute intersection, union, difference, and membership operations on sets. (Click to check)

4. Dictionaries: Key-Value Pairs (Questions 31-40)

Question 31: Creating and Querying Keys

Task: Create a dictionary containing student details: Name, Grade, and GPA. Query and print the GPA value.

Answer:


main.pyRunnable
student_record = {
    "name": "Sarah Miller",
    "grade": "11th",
    "gpa": 3.92
}

print("GPA Value:", student_record["gpa"])

Question 32: Adding and Updating Key Values

Task: Take the student_record from Question 31. Update the GPA value to 3.98 and add a new key "enrolled_courses" initialized as a list containing "Calculus".

Answer:


main.pyRunnable
student_record = {
    "name": "Sarah Miller",
    "grade": "11th",
    "gpa": 3.92
}

student_record["gpa"] = 3.98
student_record["enrolled_courses"] = ["Calculus"]

print("Updated Record:", student_record)

Question 33: Extracting Dictionary Metadata

Task: Extract all keys and values separately from a dictionary tracking class averages as list structures. Print the first course and its corresponding class average using index references from the extracted lists.

Answer:


main.pyRunnable
class_averages = {
    "Calculus": 88,
    "Chemistry": 85,
    "English Lit": 91
}

## Extract list of keys and values directly
courses = list(class_averages.keys())
scores = list(class_averages.values())

print("First Course Key:", courses[0])
print("First Course Score:", scores[0])

Question 34: Safe Retrieval Operations

Task: Use .get() to query a dictionary of course grades for "Physics", supplying a default fallback score of 0 if the key does not exist.

Answer:


main.pyRunnable
report_card = {
    "Calculus": 92,
    "Chemistry": 87
}

## "Physics" is not in the dictionary, so get() returns our fallback value of 0
physics_score = report_card.get("Physics", 0)
print("Physics Grade:", physics_score)

Question 35: Deleting Keys

Task: Remove the key "Chemistry" from a dictionary of course scores using pop(), saving the value for later printing.

Answer:


main.pyRunnable
grades = {
    "Calculus": 92,
    "Chemistry": 87,
    "English Lit": 91
}

removed_score = grades.pop("Chemistry")

print("Remaining Grades:", grades)
print("Deleted Score Value:", removed_score)

Question 36: Querying Multi-Dimensional Nested Dicts

Task: Access and print the email address of student "S002" from the following nested directory database:


main.pyRunnable
directory = {
    "S001": {"name": "Alice", "email": "alice@school.edu"},
    "S002": {"name": "Bob", "email": "bob@school.edu"}
}

Answer:


main.pyRunnable
directory = {
    "S001": {"name": "Alice", "email": "alice@school.edu"},
    "S002": {"name": "Bob", "email": "bob@school.edu"}
}

bob_email = directory["S002"]["email"]
print("S002 Email:", bob_email)

Question 37: Merging Dictionaries

Task: Merge a student's core details dictionary and their contact details dictionary.

Answer:


main.pyRunnable
core_profile = {"name": "Marcus", "grade": "10th"}
contact_info = {"email": "marcus@school.edu", "phone": "555-0143"}

core_profile.update(contact_info)
print("Merged Profile Dictionary:", core_profile)

Question 38: Updating Dictionary State

Task: Take an inventory tracker dictionary. Add 5 units to "Laptops" and update "Monitors" to a constant value of 10. Print the updated inventory.

Answer:


main.pyRunnable
inventory = {
    "Laptops": 12,
    "Monitors": 8,
    "Keyboards": 15
}

inventory["Laptops"] += 5
inventory["Monitors"] = 10

print("Updated Inventory Levels:", inventory)

Question 39: Key Existence Verification

Task: Verify if the student ID "S108" exists inside a directory dictionary, outputting the result directly as a Boolean variable.

Answer:


main.pyRunnable
directory = {
    "S101": "Alice",
    "S102": "Bob"
}

target_id = "S108"
is_registered = target_id in directory

print("Student registration status verified:", is_registered)

Question 40: Manual Value Adjustments

Task: Take a dictionary containing decimal ratios. Manually convert the ratios for both keys to whole percentage integers and update the dictionary.

Answer:


main.pyRunnable
ratios = {
    "Alice": 0.95,
    "Bob": 0.88
}

ratios["Alice"] = int(ratios["Alice"] * 100)
ratios["Bob"] = int(ratios["Bob"] * 100)

print("Updated Percentage Scores:", ratios)

Section Checkup

Check to complete: I can read and write dictionary structures and update key-value pairs. (Click to check)
Check to complete: I can use .get() to safely query keys and handle missing values. (Click to check)

5. Strings: Text Manipulation (Questions 41-50)

Question 41: Character Index Access

Task: Print the first and last characters of a text string variable named system_code.

Answer:


main.pyRunnable
system_code = "PynexHost"

first_char = system_code[0]
last_char = system_code[-1]

print(f"First Character: {first_char} | Last Character: {last_char}")

Question 42: Parsing Email Domains

Task: Slice a student email string to extract the username (everything before the @ symbol).

Answer:


main.pyRunnable
email_address = "marcus_vance@school.edu"

## Find index location of the separator symbol
at_index = email_address.find("@")
username = email_address[:at_index]

print("Extracted Username:", username)

Question 43: Case Formatting

Task: Convert a raw mixed-case course string "iNTrOdUcTiOn tO cAlCuLuS" into lower, upper, and proper Title case formats.

Answer:


main.pyRunnable
raw_string = "iNTrOdUcTiOn tO cAlCuLuS"

print("Lower Case:", raw_string.lower())
print("Upper Case:", raw_string.upper())
print("Title Case:", raw_string.title())

Question 44: Sub-String Searching

Task: Verify if the word "database" exists inside an essay string using the in operator, and find its exact character starting index.

Answer:


main.pyRunnable
essay = "Advanced network protocols and database systems are integrated."

contains_word = "database" in essay
start_index = essay.find("database")

print("Word 'database' exists:", contains_word)
print("Starts at index location:", start_index)

Question 45: Replacing Text Characters

Task: Fix a spelling typo in an announcement string by replacing all instances of "Tuesdy" with "Tuesday".

Answer:


main.pyRunnable
announcement = "The server maintenance scheduled for Tuesdy has been moved."

fixed_text = announcement.replace("Tuesdy", "Tuesday")
print("Corrected Announcement:", fixed_text)

Question 46: Parsing Comma-Separated Values

Task: Split a comma-separated string roster of student names into a Python list of individual elements.

Answer:


main.pyRunnable
roster_data = "Alice,Bob,Charlie,David"

roster_list = roster_data.split(",")
print("Parsed Roster List:", roster_list)

Question 47: Merging Lists to Strings

Task: Merge a Python list of subject strings into a single formatted string separated by the connector " | ".

Answer:


main.pyRunnable
subjects = ["Calculus", "Physics", "Chemistry", "English Lit"]

formatted_string = " | ".join(subjects)
print("Formatted Output:", formatted_string)

Question 48: Character Class Validation

Task: Check if a student ID string contains purely numeric digits, and if a system username contains purely alphabetical characters.

Answer:


main.pyRunnable
student_id = "89112"
username = "MarcusVance"

print("ID contains digits only:", student_id.isdigit())
print("Username contains alphabetical letters only:", username.isalpha())

Question 49: Output Alignment (f-strings)

Task: Construct a formatted report line using f-strings where the name is left-aligned to 10 characters, the subject is left-aligned to 12 characters, and the numeric grade is right-aligned to 5 characters with 1 decimal place.

Answer:


main.pyRunnable
student_name = "Marcus"
subject = "Chemistry"
score = 88.5

report_line = f"Student: {student_name:<10} | Subject: {subject:<12} | Score: {score:>5.1f}%"
print(report_line)

Question 50: Trimming White Space

Task: Clean up user form entry inputs by removing extra surrounding spaces and newline characters from a name entry.

Answer:


main.pyRunnable
raw_entry = "   Marcus Vance   \n"

clean_entry = raw_entry.strip()
print(f"Original: '{raw_entry}'")
print(f"Cleaned Name: '{clean_entry}'")

Congratulations! 🎓

You have completed all 50 procedural Data Structures practice questions! You are fully prepared to build applications using robust collections. Keep practicing and happy coding!

Finished this lesson?

Mark it complete to advance your curriculum progress.

5 / 23

Data Structures Practice Questions

Practice Questions - Python 3 Data Collections