enumerate() function in Python - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to use enumerate to get index and value from the list.

Python

fruits = ['apple', 'banana', 'cherry']
for [1], fruit in enumerate(fruits):
    print(f"[1]: {fruit}")

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

Aindex

Bi

Ccount

Dnum

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong variable name that is not assigned by enumerate.

Forgetting that enumerate returns two values.

The enumerate function returns pairs of (index, value). The first variable should be the index, commonly named i.

2fill in blank

medium

Complete the code to start enumerate counting from 1 instead of 0.

Python

colors = ['red', 'green', 'blue']
for idx, color in enumerate(colors, [1]):
    print(f"{idx}: {color}")

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

A0

B2

C1

D-1

Attempts:

3 left

💡 Hint

Common Mistakes

Passing 0 which is the default and does not change the start.

Passing a negative number which is unusual for indexing.

The second argument to enumerate sets the starting index. Using 1 starts counting from 1.

3fill in blank

hard

Fix the error in the code to correctly unpack the values from enumerate.

Python

items = ['pen', 'pencil', 'eraser']
for [1] in enumerate(items):
    print(f"{index}: {item}")

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

Aidx, val

Bitem

Ci

Dindex, item

Attempts:

3 left

💡 Hint

Common Mistakes

Using only one variable to unpack two values.

Using variable names that don't match in the print statement.

enumerate returns two values per loop: the index and the item. You must unpack both.

4fill in blank

hard

Fill both blanks to create a dictionary with index as key and item as value using enumerate.

Python

items = ['a', 'b', 'c']
indexed = [1](items)
result = {idx: [2] for idx, val in indexed}

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

Aenumerate

Bval

Cidx

Dlist

Attempts:

3 left

💡 Hint

Common Mistakes

Using list instead of enumerate.

Using the index as the dictionary value instead of the item.

Use enumerate to get index and value pairs. Then use the value val as dictionary values.

5fill in blank

hard

Fill all three blanks to create a list of strings showing index and item using enumerate.

Python

words = ['dog', 'cat', 'bird']
result = [f"[1]: [2]" for [3], word in enumerate(words)]

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

Ai

Bword

Cindex

Dj

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names inconsistently.

Using the wrong variable for index or item.

The variable i is the index from enumerate, and word is the item. Use i and word in the formatted string and for loop.

Practice

1. What does the enumerate() function do in Python?

easy

A. It counts how many items are in a list.

B. It sorts the items in a list alphabetically.

C. It reverses the order of items in a list.

D. It returns both the index and the value of items in a list during a loop.

Solution

1. Step 1: Understand the purpose of enumerate()

   The enumerate() function adds a counter to an iterable and returns it as an enumerate object.

2. Step 2: Identify what is returned during looping

   When looping, it gives both the index (position) and the value of each item.

3. Final Answer:

   It returns both the index and the value of items in a list during a loop. -> Option D

4. Quick Check:

   enumerate() = index + value [OK]

Hint: Remember: enumerate() pairs index with value [OK]

Common Mistakes:

• Thinking enumerate() sorts the list
• Assuming it only counts items
• Believing it reverses the list

2. Which of the following is the correct syntax to use enumerate() in a for loop?

easy

A. for index in enumerate(list):

B. for value, index in enumerate(list):

C. for index, value in enumerate(list):

D. for value in enumerate(list):

Solution

1. Step 1: Recall the unpacking order of enumerate()

   enumerate() returns pairs of (index, value), so the loop variables must match this order.

2. Step 2: Match the correct variable order in the for loop

   The correct syntax is for index, value in enumerate(list): to unpack both index and value properly.

3. Final Answer:

   for index, value in enumerate(list): -> Option C

4. Quick Check:

   Index comes first, then value [OK]

Hint: Index always comes before value in enumerate() [OK]

Common Mistakes:

• Swapping index and value order
• Using only one variable to unpack both
• Forgetting to unpack both values

3. What is the output of this code?

fruits = ['apple', 'banana', 'cherry']
for i, fruit in enumerate(fruits, start=1):
    print(i, fruit)

medium

A. 1 apple
2 banana
3 cherry

B. 0 apple
1 banana
2 cherry

C. apple 0
banana 1
cherry 2

D. apple 1
banana 2
cherry 3

Solution

1. Step 1: Understand the start parameter in enumerate()

   The start=1 means counting begins at 1 instead of the default 0.

2. Step 2: Trace the loop output

   Loop prints index and fruit: 1 apple, 2 banana, 3 cherry.

3. Final Answer:

   1 apple 2 banana 3 cherry -> Option A

4. Quick Check:

   start=1 shifts index to 1 [OK]

Hint: Check start value to know index numbering [OK]

Common Mistakes:

• Assuming index starts at 0 despite start=1
• Mixing up index and value order in print
• Ignoring the start parameter

4. Find the error in this code snippet:

items = ['pen', 'pencil', 'eraser']
for value, index in enumerate(items):
    print(index, value)

medium

A. There is no error; the code runs fine.

B. The variables in the for loop are reversed; index should come first.

C. The print statement syntax is incorrect.

D. enumerate() cannot be used with lists.

Solution

1. Step 1: Check the order of variables unpacked from enumerate()

   enumerate() returns (index, value), so the first variable must be index.

2. Step 2: Identify the mistake in variable order

   The code uses value, index which is reversed and causes incorrect unpacking.

3. Final Answer:

   The variables in the for loop are reversed; index should come first. -> Option B

4. Quick Check:

   Index always first in enumerate() unpacking [OK]

Hint: Index comes before value in enumerate() unpacking [OK]

Common Mistakes:

• Swapping index and value variables
• Thinking enumerate() can't be used with lists
• Misreading the error as print syntax

5. You have a list of names: names = ['Anna', 'Bob', '', 'Diana']. You want to print only non-empty names with their positions starting at 1. Which code correctly does this using enumerate()?

hard

A. for i, name in enumerate(names, start=1):
if name:
print(i, name)

B. for i, name in enumerate(names):
if name != '':
print(i, name)

C. for i, name in enumerate(names, start=0):
if name:
print(i, name)

D. for i, name in enumerate(names, start=1):
if name == '':
print(i, name)

Solution

1. Step 1: Indexing starting at 1

   Use enumerate(names, start=1) to get positions starting from 1: 1 Anna, 2 Bob, 3 (empty), 4 Diana.

2. Step 2: Skip empty names

   Use if name: since empty string '' is falsy in Python.

3. Final Answer:

   for i, name in enumerate(names, start=1): if name: print(i, name) -> Option A

4. Quick Check:

   start=1 + if name skips empty [OK]

Hint: Use start=1 and if name to skip empty strings [OK]

Common Mistakes:

• Forgetting to start counting at 1
• Printing empty strings
• Not adjusting index when using default start=0