Accessing values using keys in Python - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to access the value of the key 'name' in the dictionary.

Python

person = {'name': 'Alice', 'age': 30}
print(person[1])

Drag options to blanks, or click blank then click option'

A['location']

B['age']

C['name']

D['gender']

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses instead of square brackets.

Using a key that does not exist in the dictionary.

The key 'name' is used inside square brackets to get its value from the dictionary.

2fill in blank

medium

Complete the code to print the value of the key 'color' from the dictionary.

Python

car = {'brand': 'Toyota', 'color': 'red', 'year': 2020}
print(car[1])

Drag options to blanks, or click blank then click option'

A['model']

B['color']

C['year']

D['brand']

Attempts:

3 left

💡 Hint

Common Mistakes

Using a key that is not in the dictionary.

Forgetting to put the key name in quotes.

To get the color of the car, use the key 'color' inside square brackets.

3fill in blank

hard

Fix the error in the code to correctly access the value of the key 'score'.

Python

results = {'score': 85, 'grade': 'B'}
print(results[1])

Drag options to blanks, or click blank then click option'

Ascore

B{score}

C(score)

D['score']

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses or curly braces instead of square brackets.

Not putting the key name in quotes.

Dictionary keys must be accessed using square brackets and the key as a string.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that maps each word to its length.

Python

words = ['apple', 'banana', 'cherry']
lengths = {word[1] for word in words if len(word) [2] 5}

Drag options to blanks, or click blank then click option'

A: len(word)

B>

C<

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using '=' instead of ':' in the dictionary comprehension.

Using the wrong comparison operator in the if condition.

The dictionary comprehension maps each word to its length using ':' and filters words longer than 5 using '>'.

5fill in blank

hard

Fill all three blanks to create a dictionary of uppercase keys and their values, filtering values greater than 10.

Python

data = {'a': 5, 'b': 15, 'c': 20}
result = [1]: [2] for k, v in data.items() if v [3] 10}

Drag options to blanks, or click blank then click option'

Ak.upper()

Bv

C>

Dk.lower()

Attempts:

3 left

💡 Hint

Common Mistakes

Using k.lower() instead of k.upper().

Using '<' or '==' instead of '>' in the condition.

The comprehension uses k.upper() as keys, v as values, and filters values greater than 10 with '>'.

Practice

1. What is the correct way to access the value associated with the key 'name' in the dictionary person = {'name': 'Alice', 'age': 30}?

easy

A. person.get('age')

B. person.name

C. person['name']

D. person['Alice']

Solution

1. Step 1: Identify the dictionary and key

   The dictionary is person and the key to access is 'name'.

2. Step 2: Use correct syntax to access value by key

   In Python, dictionary values are accessed using square brackets and the key as a string: person['name'].

3. Final Answer:

   person['name'] -> Option C

4. Quick Check:

   Access value by key = person['name'] [OK]

Hint: Use square brackets with the key string to get value [OK]

Common Mistakes:

• Using dot notation like person.name (not valid for dict)
• Using a value instead of key inside brackets
• Accessing a different key than asked

2. Which of the following is the correct syntax to safely get the value for key 'city' from dictionary data without causing an error if the key does not exist?

easy

A. data['city']

B. data.get('city')

C. data.city

D. data['City']

Solution

1. Step 1: Understand safe access in dictionaries

   Using data['city'] causes an error if the key is missing. Using data.get('city') returns None instead.

2. Step 2: Identify correct method for safe access

   The get() method is designed to safely access keys without errors.

3. Final Answer:

   data.get('city') -> Option B

4. Quick Check:

   Safe key access = data.get('city') [OK]

Hint: Use get() to avoid errors if key missing [OK]

Common Mistakes:

• Using square brackets which raise KeyError if key missing
• Using dot notation which is invalid for dict
• Using wrong key case causing KeyError

3. What will be the output of this code?

info = {'a': 1, 'b': 2, 'c': 3}
print(info['b'])

medium

A. 2

B. 1

C. 3

D. KeyError

Solution

1. Step 1: Identify the dictionary and key accessed

   The dictionary info has key 'b' with value 2.

2. Step 2: Access the value using the key

   The code prints info['b'], which is 2.

3. Final Answer:

   2 -> Option A

4. Quick Check:

   info['b'] = 2 [OK]

Hint: Look up the key's value directly in the dictionary [OK]

Common Mistakes:

• Confusing key with value
• Expecting KeyError when key exists
• Mixing up keys and values

4. The following code causes an error. What is the problem?

data = {'x': 10, 'y': 20}
print(data['z'])

medium

A. TypeError because keys must be integers

B. SyntaxError due to wrong brackets

C. No error, prints 0

D. KeyError because 'z' is not in the dictionary

Solution

1. Step 1: Check if key exists in dictionary

   The key 'z' is not present in data.

2. Step 2: Understand error caused by missing key

   Accessing a missing key with square brackets raises a KeyError.

3. Final Answer:

   KeyError because 'z' is not in the dictionary -> Option D

4. Quick Check:

   Missing key access = KeyError [OK]

Hint: Check if key exists before accessing or use get() [OK]

Common Mistakes:

• Assuming missing keys return 0 or None
• Confusing syntax error with runtime error
• Using wrong bracket types

5. Given the dictionary grades = {'Alice': 85, 'Bob': 92, 'Charlie': 78}, which code snippet correctly prints Bob's grade or 'Not found' if Bob is not in the dictionary?

hard

A. print(grades.get('Bob', 'Not found'))

B. print(grades['Bob'] or 'Not found')

C. print(grades['bob'] or 'Not found')

D. print(grades.get('Bob'))

Solution

1. Step 1: Understand the goal

   We want to print Bob's grade if present, otherwise print 'Not found'.

2. Step 2: Analyze each option

   print(grades['Bob'] or 'Not found') will raise KeyError if key missing because access happens before 'or'. print(grades.get('Bob', 'Not found')) uses get() with default value, which is concise and safe. print(grades['bob'] or 'Not found') uses wrong key case and will fail. print(grades.get('Bob')) prints None if key missing, not 'Not found'.

3. Final Answer:

   print(grades.get('Bob', 'Not found')) -> Option A

4. Quick Check:

   Use get() with default for safe access [OK]

Hint: Use get(key, default) to handle missing keys easily [OK]

Common Mistakes:

• Using wrong key case causing missing key
• Not providing default value in get()
• Assuming or operator works for missing keys