grep and grepl in R Programming - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to find the indices of elements containing the letter 'a'.

R Programming

words <- c("apple", "banana", "cherry", "date")
indices <- grep([1], words)
print(indices)

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

A"c"

B"b"

C"a"

D"d"

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to put the pattern inside quotes.

Using the wrong letter in the pattern.

The grep function returns the indices of elements that match the pattern. Here, we look for the letter 'a'.

2fill in blank

medium

Complete the code to check which elements contain the letter 'e' and return TRUE or FALSE.

R Programming

words <- c("apple", "banana", "cherry", "date")
contains_e <- grepl([1], words)
print(contains_e)

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A"e"

B"o"

C"a"

D"i"

Attempts:

3 left

💡 Hint

Common Mistakes

Using grep instead of grepl when expecting TRUE/FALSE.

Using a letter not present in any word.

The grepl function returns a logical vector indicating if the pattern is found in each element. Here, we check for 'e'.

3fill in blank

hard

Fix the error in the code to correctly find words containing 'n'.

R Programming

words <- c("apple", "banana", "cherry", "date")
result <- grep([1], words, value = TRUE)
print(result)

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

An

B"n"

C'n'

Dn"

Attempts:

3 left

💡 Hint

Common Mistakes

Not using quotes around the pattern.

Using mismatched or incomplete quotes.

The pattern must be a string in quotes. Without quotes, R treats it as a variable, causing an error.

4fill in blank

hard

Fill both blanks to create a named logical vector showing which words contain 'a'.

R Programming

words <- c("apple", "banana", "cherry", "date")
result <- setNames(grepl([1], words), [2])
print(result)

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

A"a"

Bwords

C"words"

Dletters

Attempts:

3 left

💡 Hint

Common Mistakes

Using quotes around the second blank, which should be a variable.

Using the wrong pattern string.

grepl checks for 'a' in each word. setNames assigns the original words as names to the logical vector.

5fill in blank

hard

Fill all three blanks to create a named vector of words containing 'e' with their indices.

R Programming

words <- c("apple", "banana", "cherry", "date")
indices <- grep([1], words)
selected_words <- words[[2]]
named_vector <- setNames(selected_words, [3])
print(named_vector)

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

A"e"

Bindices

D"words"

Attempts:

3 left

💡 Hint

Common Mistakes

Using quotes around indices in the second or third blank.

Using the wrong pattern string.

We search for 'e' with grep, get indices, select words at those indices, and name them with the same indices.