Data frame creation in R Programming - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this data frame creation?

Consider the following R code that creates a data frame. What will be the output when printed?

R Programming

df <- data.frame(Name = c("Anna", "Bob"), Age = c(25, 30))
print(df)

A

  Name Age
1 Anna  25
2 Bob   30

B

  Name Age
1 Anna  30
2 Bob   25

C

  Name Age
1 25   Anna
2 30   Bob

D Error: object 'df' not found

💡 Hint

Look at how vectors are assigned to columns in data.frame.

The data frame is created with two columns: Name and Age. The vectors are assigned in order, so Anna is 25 and Bob is 30.

❓ Predict Output

intermediate

What is the number of rows in this data frame?

Given this R code, how many rows does the data frame 'df' have?

R Programming

df <- data.frame(ID = 1:4, Score = c(88, 92, 79, 85))
nrow(df)

A 1

B 2

C 4

D Error: object 'df' not found

💡 Hint

nrow() returns the number of rows in a data frame.

The data frame has 4 rows because the vectors have length 4.

🔧 Debug

advanced

Why does this data frame creation code produce an error?

Examine the code below. Why does it cause an error when run?

R Programming

df <- data.frame(Name = c("Alice", "Bob"), Age = c(30))

A Because Age vector must be a factor, not numeric

B Because the vectors for columns have different lengths

C Because the Name vector is missing a closing quote

D Because the data.frame function requires numeric columns only

💡 Hint

Check if all columns have the same number of elements.

In R, data frame columns must have equal length. Here, Name has length 2 but Age has length 1, causing an error.

🧠 Conceptual

advanced

What happens if you create a data frame with a list column?

Consider this R code creating a data frame with a list column. What is the structure of the resulting data frame?

R Programming

df <- data.frame(ID = 1:2, Values = I(list(c(1,2), c(3,4))))
str(df)

A A data frame with 2 rows and a list column where each cell contains a numeric vector

B A data frame with 2 rows and a numeric column with combined values

C An error because data frames cannot have list columns

D A data frame with 4 rows, each with a single numeric value

💡 Hint

The I() function inhibits conversion and allows list columns.

Using I() wraps the list so the data frame keeps each list element as a cell, allowing complex data in columns.

❓ Predict Output

expert

What is the output of this complex data frame creation?

What will be printed when running this R code?

R Programming

df <- data.frame(
  Name = c("Tom", "Jerry"),
  Age = c(5, 7),
  stringsAsFactors = FALSE
)
df$Age <- df$Age + 1
print(df)

A

   Name Age
1   Tom  51
2 Jerry  71

B

   Name Age
1   Tom   5
2 Jerry   7

C Error: object 'df' not found

D

   Name Age
1   Tom   6
2 Jerry   8

💡 Hint

Adding 1 to the Age column increases each age by one.

The Age column values are incremented by 1, so 5 becomes 6 and 7 becomes 8.