strsplit in R Programming - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to split the string 'apple,banana,cherry' by commas.

R Programming

result <- strsplit("apple,banana,cherry", [1])

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

A","

B" "

C";"

D"-"

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong separator like a semicolon or space.

Not putting the separator inside quotes.

The strsplit function splits a string by the specified separator. Here, the separator is a comma, so we use ",".

2fill in blank

medium

Complete the code to split the string 'one|two|three' by the pipe character.

R Programming

result <- strsplit("one|two|three", [1])

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

A"\\|"

B"|"

C"||"

D"\\\\|"

Attempts:

3 left

💡 Hint

Common Mistakes

Using just "|" without escaping causes unexpected splitting.

Using "\\\\|" which overescapes in R strings.

In R, the pipe character '|' is a special symbol in regular expressions, so it must be escaped with "\\|" to be used as a literal separator.

3fill in blank

hard

Fix the error in splitting the string 'a,b;c' by commas and semicolons.

R Programming

result <- strsplit("a,b;c", [1])

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

A";,"

B",;"

C"[,;]"

Attempts:

3 left

💡 Hint

Common Mistakes

Using a string with both separators without brackets.

Using separators without escaping special characters.

To split by multiple characters like comma and semicolon, use a regular expression with square brackets: "[,;]".

4fill in blank

hard

Fill both blanks to split the string 'red|green|blue' by pipe and get the first element.

R Programming

parts <- strsplit("red|green|blue", [1])
first_color <- parts[[1]][2]

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

A"\\|"

B[[1]]

C[1]

D"|"

Attempts:

3 left

💡 Hint

Common Mistakes

Not escaping the pipe character correctly.

Using single brackets [1] which returns a list, not a vector.

The pipe character must be escaped as "\\|" in strsplit. The result is a list, so to get the first element use [[1]].

5fill in blank

hard

Fill all three blanks to split 'cat,dog;bird' by commas or semicolons and get the second word.

R Programming

words <- strsplit("cat,dog;bird", [1])
second_word <- words[2][3]

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

A"[,;]"

B[[1]]

C[2]

D[1]

Attempts:

3 left

💡 Hint

Common Mistakes

Using single brackets [1] instead of double brackets [[1]] to extract list element.

Not using the correct regex pattern for multiple separators.

Use "[,;]" to split by comma or semicolon. The result is a list, so use [[1]] to get the vector, then [2] to get the second word.

Practice

1. What does the strsplit function in R do?

easy

A. It joins multiple strings into one string.

B. It counts the number of characters in a string.

C. It converts a string to uppercase letters.

D. It breaks a string into parts based on a separator.

Solution

1. Step 1: Understand the purpose of strsplit

   The strsplit function is designed to split a string into smaller parts using a specified separator.

2. Step 2: Compare options with function behavior

   Only It breaks a string into parts based on a separator. correctly describes this behavior. Options A, C, and D describe different string functions.

3. Final Answer:

   It breaks a string into parts based on a separator. -> Option D

4. Quick Check:

   strsplit splits strings = B [OK]

Hint: Remember: strsplit splits strings by separator [OK]

Common Mistakes:

• Confusing strsplit with paste or toupper functions
• Thinking strsplit counts characters
• Assuming strsplit joins strings

2. Which of the following is the correct syntax to split the string "apple,banana,orange" by commas using strsplit?

easy

A. strsplit("apple,banana,orange", " ")

B. strsplit("apple,banana,orange", ".")

C. strsplit("apple,banana,orange", ",")

D. strsplit("apple,banana,orange")

Solution

1. Step 1: Identify the separator in the string

   The string uses commas "," to separate words.

2. Step 2: Match the separator in strsplit syntax

   strsplit("apple,banana,orange", ",") uses "," as the separator, which is correct. strsplit("apple,banana,orange", ".") uses ".", C uses space, and D misses the separator argument.

3. Final Answer:

   strsplit("apple,banana,orange", ",") -> Option C

4. Quick Check:

   Separator matches comma = A [OK]

Hint: Use the exact separator character inside quotes [OK]

Common Mistakes:

• Forgetting to provide the separator argument
• Using wrong separator character
• Using unquoted separator

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

result <- strsplit("one-two-three", "-")
print(result)

medium

A. [[1]] "one" "two" "three"

B. "one-two-three"

C. [1] "one" "two" "three"

D. Error: invalid separator

Solution

1. Step 1: Understand strsplit output type

   strsplit returns a list where each element is a character vector of split parts.

2. Step 2: Analyze the printed output

   The print shows a list with one element ([[1]]) containing the split strings "one", "two", "three".

3. Final Answer:

   [[1]] "one" "two" "three" -> Option A

4. Quick Check:

   strsplit returns list of vectors = A [OK]

Hint: Remember strsplit returns a list, not a vector directly [OK]

Common Mistakes:

• Expecting a simple vector instead of a list
• Confusing output with a single string
• Thinking strsplit throws an error for valid separator

4. Identify the error in this R code:

strsplit("cat,dog,bird", ",")[[2]]

medium

A. The string should be a vector, not a single string.

B. Index [[2]] is out of bounds because strsplit returns a list of length 1.

C. Missing parentheses around strsplit call.

D. Separator "," is incorrect for splitting.

Solution

1. Step 1: Check the output structure of strsplit

   strsplit returns a list with one element per input string. Here, input is one string, so list length is 1.

2. Step 2: Analyze the indexing [[2]]

   Trying to access [[2]] causes an out-of-bounds error because the list has only one element.

3. Final Answer:

   Index [[2]] is out of bounds because strsplit returns a list of length 1. -> Option B

4. Quick Check:

   List length 1, index 2 invalid = D [OK]

Hint: Check list length before using [[index]] [OK]

Common Mistakes:

• Assuming strsplit returns multiple list elements for one string
• Using wrong separator
• Misunderstanding list indexing

5. You have a vector of strings: c("red:blue", "green:yellow", "black:white"). How do you split each string by ":" and get a flat vector of all colors?

hard

A. unlist(strsplit(c("red:blue", "green:yellow", "black:white"), ":"))

B. strsplit(c("red:blue", "green:yellow", "black:white"), ":")

C. paste(strsplit(c("red:blue", "green:yellow", "black:white"), ":"))

D. split(c("red:blue", "green:yellow", "black:white"), ":")

Solution

1. Step 1: Use strsplit to split each string by ":"

   strsplit returns a list of character vectors for each element in the input vector.

2. Step 2: Flatten the list to a single vector

   Using unlist converts the list of vectors into one flat character vector containing all colors.

3. Final Answer:

   unlist(strsplit(c("red:blue", "green:yellow", "black:white"), ":")) -> Option A

4. Quick Check:

   Use unlist to flatten strsplit output = C [OK]

Hint: Use unlist() to flatten strsplit list output [OK]

Common Mistakes:

• Forgetting to unlist and getting a list instead of vector
• Using paste which concatenates instead of splitting
• Using split which is for factors, not strings