Membership operators (in, not in) in Python - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if 'apple' is in the list.

Python

fruits = ['apple', 'banana', 'cherry']
if 'apple' [1] fruits:
    print('Found apple!')

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

Anot in

Bcontains

Cin

Dhas

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'not in' instead of 'in'.

Using 'contains' which is not a Python operator.

The in operator checks if an item exists in a list.

2fill in blank

medium

Complete the code to check if 'dog' is NOT in the list.

Python

animals = ['cat', 'bird', 'fish']
if 'dog' [1] animals:
    print('Dog is not here!')

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

Acontains

Bnot in

Cin

Dhas

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'in' instead of 'not in'.

Using 'contains' which is not a Python operator.

The not in operator checks if an item does not exist in a list.

3fill in blank

hard

Fix the error in the code to check membership correctly.

Python

colors = ['red', 'green', 'blue']
if 'yellow' [1] colors:
    print('Yellow is in the list')
else:
    print('Yellow is not in the list')

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

Ain

Bnot in

Cinside

Dhas

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'not in' when the logic requires 'in'.

Using invalid operators like 'inside' or 'has'.

The in operator is correct because the if block prints 'Yellow is in the list' when the item is present, and else when not.

4fill in blank

hard

Fill both blanks to create a dictionary of words and their lengths only if length is greater than 3.

Python

words = ['sun', 'moon', 'star', 'sky']
lengths = {word: [1] for word in words if len(word) [2] 3}

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

Alen(word)

B>

C<

Dword

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>'.

Using 'word' instead of 'len(word)'.

We use len(word) to get the length and > to check if length is greater than 3.

5fill in blank

hard

Fill all three blanks to create a dictionary with uppercase keys and values only if value is not in the list.

Python

values = ['a', 'b', 'c']
result = { [1]: [2] for [3] in values if [2] not in ['b', 'c']}

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

Av.upper()

Bv

Dk

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'k' as loop variable when it is not defined.

Mixing keys and values incorrectly.

We use v.upper() for keys, v for values, and iterate with v over values.

Practice

1. What does the in operator do in Python?

easy

A. Creates a new collection

B. Adds a value to a collection

C. Removes a value from a collection

D. Checks if a value exists inside a collection

Solution

1. Step 1: Understand the purpose of in

   The in operator is used to check if a value is present inside a collection like a list, string, or tuple.

2. Step 2: Compare with other options

   Options A, B, and C describe actions unrelated to membership checking.

3. Final Answer:

   Checks if a value exists inside a collection -> Option D

4. Quick Check:

   in means membership check [OK]

Hint: Remember: in means 'is inside' [OK]

Common Mistakes:

• Confusing in with adding or removing items
• Thinking in changes the collection
• Mixing in with comparison operators

2. Which of the following is the correct syntax to check if the string 'apple' is NOT in the list fruits?

easy

A. if 'apple' not in fruits:

B. if 'apple' not fruits:

C. if not 'apple' fruits:

D. if 'apple' !in fruits:

Solution

1. Step 1: Recall correct syntax for not in

   The correct syntax to check absence is value not in collection.

2. Step 2: Evaluate each option

   if 'apple' not in fruits: matches correct syntax. if 'apple' not fruits: misses in. if not 'apple' fruits: misses in. if 'apple' !in fruits: uses invalid operator !in.

3. Final Answer:

   if 'apple' not in fruits: -> Option A

4. Quick Check:

   Use not in as two words [OK]

Hint: Use not in as two words, no symbols [OK]

Common Mistakes:

• Writing !in instead of not in
• Omitting in after not
• Using not 'value' in which is valid but less clear

3. What is the output of this code?

letters = ['a', 'b', 'c']
print('d' in letters)
print('a' not in letters)

medium

A. True\nTrue

B. False\nTrue

C. False\nFalse

D. True\nFalse

Solution

1. Step 1: Check if 'd' is in the list

   'd' is not in ['a', 'b', 'c'], so 'd' in letters is False.

2. Step 2: Check if 'a' is not in the list

   'a' is in the list, so 'a' not in letters is False, so print('a' not in letters) prints False.

3. Final Answer:

   False False is incorrect because the second print outputs False, but the first print outputs False, so the correct output is False False which matches False\nFalse.

4. Quick Check:

   'd' in letters = False, 'a' not in letters = False [OK]

Hint: Check each membership separately [OK]

Common Mistakes:

• Assuming 'd' is in the list
• Mixing up in and not in results
• Confusing True/False outputs

4. Find the error in this code snippet:

items = ['pen', 'pencil', 'eraser']
if 'pen' not items:
    print('Pen is missing')

medium

A. Incorrect print statement syntax

B. Wrong list name

C. Missing in after not

D. No error, code is correct

Solution

1. Step 1: Check the membership syntax

   The correct syntax for checking absence is value not in collection. The code misses in after not.

2. Step 2: Verify other parts

   List name and print statement are correct. The only error is missing in.

3. Final Answer:

   Missing in after not -> Option C

4. Quick Check:

   Use not in together [OK]

Hint: Always write not in together [OK]

Common Mistakes:

• Writing not items instead of not in items
• Forgetting in keyword
• Assuming not alone checks membership

5. You have a list words = ['cat', 'dog', 'bird']. You want to print all words that are NOT in the string text = 'I have a dog and a cat'. Which code correctly does this?

hard

A. for w in words:
if w not in text:
print(w)

B. for w in words:
if w in text:
print(w)

C. for w in words:
if not w text:
print(w)

D. for w in words:
if w not text:
print(w)

Solution

1. Step 1: Understand the goal

   We want to print words from the list that are NOT found inside the string text.

2. Step 2: Check each option's logic

   for w in words: if w not in text: print(w) uses if w not in text, which correctly checks absence. for w in words: if w in text: print(w) prints words that ARE in text, opposite of goal. for w in words: if not w text: print(w) has syntax error, missing in after w. for w in words: if w not text: print(w) has syntax error missing in.

3. Final Answer:

   for w in words: if w not in text: print(w) -> Option A

4. Quick Check:

   Use not in for absence check [OK]

Hint: Use if w not in text to find missing words [OK]

Common Mistakes:

• Omitting in keyword in various positions
• Forgetting in keyword
• Printing words that are present instead of absent