Take, drop, and chunked in Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to take the first 3 elements from the list.

Kotlin

val numbers = listOf(1, 2, 3, 4, 5)
val firstThree = numbers.[1](3)
println(firstThree)

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

Atake

Bdrop

Cchunked

Dslice

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'drop' will skip elements instead of taking them.

Using 'chunked' splits the list into groups, not just taking elements.

The take function returns the first n elements from the list.

2fill in blank

medium

Complete the code to drop the first 2 elements from the list.

Kotlin

val letters = listOf("a", "b", "c", "d")
val afterDrop = letters.[1](2)
println(afterDrop)

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

Atake

Bchunked

Cdrop

Dslice

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'take' will select elements instead of skipping them.

Using 'chunked' groups elements but does not drop.

The drop function skips the first n elements and returns the rest.

3fill in blank

hard

Fix the error in the code to split the list into chunks of size 2.

Kotlin

val nums = listOf(10, 20, 30, 40, 50)
val chunks = nums.[1](2)
println(chunks)

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

Achunked

Bdrop

Ctake

Dslice

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'take' or 'drop' will not split the list into chunks.

Using 'slice' requires ranges, not chunk sizes.

The chunked function splits the list into sublists of the given size.

4fill in blank

hard

Fill both blanks to take the first 4 elements and then drop 2 from them.

Kotlin

val data = listOf(5, 6, 7, 8, 9)
val result = data.[1](4).[2](2)
println(result)

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

Atake

Bdrop

Cchunked

Dslice

Attempts:

3 left

💡 Hint

Common Mistakes

Reversing the order of 'take' and 'drop' changes the result.

Using 'chunked' instead of 'drop' or 'take' here is incorrect.

First, take(4) selects the first 4 elements, then drop(2) removes the first 2 from that selection.

5fill in blank

hard

Fill all three blanks to chunk the list into size 3, then take the first chunk, and drop its first element.

Kotlin

val items = listOf("x", "y", "z", "w", "v", "u")
val processed = items.[1](3).[2](1)[0].[3](1)
println(processed)

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

Achunked

Btake

Cdrop

Dslice

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'drop' instead of 'take' to select the first chunk will skip chunks and select a different one.

Trying to use 'slice' instead of 'chunked' to split the list.

First, chunked(3) splits the list into chunks of 3. Then take(1) selects the first chunk (as a singleton list), [0] extracts the chunk list itself, finally drop(1) removes the first element from that chunk.

Practice

1. What does the Kotlin function take(3) do when called on a list?

easy

A. Returns the first 3 items of the list

B. Removes the first 3 items from the list

C. Splits the list into chunks of size 3

D. Returns the last 3 items of the list

Solution

1. Step 1: Understand the take function

   The take(n) function returns the first n elements from a list.

2. Step 2: Apply to the example

   Calling take(3) returns the first 3 items, not removing or splitting the list.

3. Final Answer:

   Returns the first 3 items of the list -> Option A

4. Quick Check:

   take(3) = first 3 items [OK]

Hint: Remember: take(n) grabs first n items [OK]

Common Mistakes:

• Confusing take with drop
• Thinking take removes items
• Mixing take with chunked

2. Which of the following is the correct syntax to split a list myList into chunks of size 4 in Kotlin?

easy

A. myList.take(4)

B. chunked(myList, 4)

C. myList.drop(4)

D. myList.chunked(4)

Solution

1. Step 1: Identify the chunked function usage

   The chunked(size) function is called as a method on the list with the chunk size as argument.

2. Step 2: Check each option

   Only myList.chunked(4) matches the correct syntax. Others are either wrong method or wrong call style.

3. Final Answer:

   myList.chunked(4) -> Option D

4. Quick Check:

   chunked called as method with size [OK]

Hint: chunked is a method: list.chunked(size) [OK]

Common Mistakes:

• Using chunked as a standalone function
• Confusing chunked with take or drop
• Wrong argument order

3. What is the output of the following Kotlin code?

val numbers = listOf(10, 20, 30, 40, 50, 60)
val result = numbers.drop(2).take(3)
println(result)

medium

A. [40, 50, 60]

B. [10, 20, 30]

C. [30, 40, 50]

D. [20, 30, 40]

Solution

1. Step 1: Apply drop(2) on the list

   Dropping first 2 items removes 10 and 20, leaving [30, 40, 50, 60].

2. Step 2: Apply take(3) on the dropped list

   Taking first 3 items from [30, 40, 50, 60] gives [30, 40, 50].

3. Final Answer:

   [30, 40, 50] -> Option C

4. Quick Check:

   drop(2) then take(3) = [30, 40, 50] [OK]

Hint: drop removes first n, then take picks next n [OK]

Common Mistakes:

• Taking before dropping
• Off-by-one errors in indexing
• Confusing drop and take order

4. Identify the error in this Kotlin code snippet:

val list = listOf(1, 2, 3, 4, 5)
val chunks = list.chunked(0)
println(chunks)

medium

A. listOf cannot be used with chunked

B. chunked size cannot be zero

C. Missing import for chunked function

D. drop should be used instead of chunked

Solution

1. Step 1: Understand chunked parameter requirements

   The chunked(size) function requires a positive integer size greater than zero.

2. Step 2: Analyze the code

   Using chunked(0) is invalid and will throw an IllegalArgumentException.

3. Final Answer:

   chunked size cannot be zero -> Option B

4. Quick Check:

   chunked size > 0 [OK]

Hint: chunked size must be positive, never zero [OK]

Common Mistakes:

• Using zero or negative chunk size
• Assuming chunked works like drop
• Ignoring runtime exceptions

5. Given a list val data = listOf(1, 2, 3, 4, 5, 6, 7), which Kotlin expression produces a list of chunks of size 3, but only for the last 6 elements?

hard

A. data.drop(1).chunked(3)

B. data.take(6).chunked(3)

C. data.chunked(3).drop(1)

D. data.chunked(3).take(2)

Solution

1. Step 1: Identify last 6 elements

   Using drop(1) removes the first element, leaving last 6 elements [2,3,4,5,6,7].

2. Step 2: Chunk the remaining list

   Calling chunked(3) on [2,3,4,5,6,7] splits it into [[2,3,4], [5,6,7]].

3. Final Answer:

   data.drop(1).chunked(3) -> Option A

4. Quick Check:

   drop(1) then chunked(3) = last 6 in chunks [OK]

Hint: Drop first, then chunk to get last elements in groups [OK]

Common Mistakes:

• Using take instead of drop for last elements
• Chunking before dropping
• Miscounting chunk sizes