summarise() with group_by() in R Programming - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to group the data by 'cyl' column.

R Programming

library(dplyr)
data <- mtcars
grouped_data <- data %>% group_by([1])

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

Acyl

Bmpg

Chp

Dgear

Attempts:

3 left

💡 Hint

Common Mistakes

Using a column that is not categorical for grouping.

Forgetting to load dplyr library.

We use group_by(cyl) to group the data by the number of cylinders.

2fill in blank

medium

Complete the code to calculate the average miles per gallon (mpg) for each group.

R Programming

library(dplyr)
data <- mtcars
grouped_data <- data %>% group_by(cyl) %>% summarise(avg_mpg = [1](mpg))

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

Asum

Bmean

Cmedian

Dmax

Attempts:

3 left

💡 Hint

Common Mistakes

Using sum instead of mean, which gives total not average.

Using max or median which are different statistics.

The mean() function calculates the average mpg for each cylinder group.

3fill in blank

hard

Fix the error in the summarise() function to count the number of cars in each group.

R Programming

library(dplyr)
data <- mtcars
grouped_data <- data %>% group_by(cyl) %>% summarise(count = [1]())

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

Asum

Blength

Ccount

Dn

Attempts:

3 left

💡 Hint

Common Mistakes

Using length() which does not work inside summarise for grouped data.

Using count() which is not a function inside summarise.

The n() function counts the number of rows in each group inside summarise().

4fill in blank

hard

Fill both blanks to calculate the average horsepower (hp) and maximum weight (wt) for each group.

R Programming

library(dplyr)
data <- mtcars
grouped_data <- data %>% group_by(cyl) %>% summarise(avg_hp = [1](hp), max_wt = [2](wt))

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

Amean

Bmax

Cmin

Dsum

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up min and max functions.

Using sum instead of mean for average.

Use mean() to get average horsepower and max() to get maximum weight per group.

5fill in blank

hard

Fill all three blanks to group by 'gear', then calculate the count, average mpg, and minimum quarter mile time (qsec).

R Programming

library(dplyr)
data <- mtcars
grouped_data <- data %>% group_by([1]) %>% summarise(count = [2](), avg_mpg = [3](mpg), min_qsec = min(qsec))

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

Agear

Bn

Cmean

Dsum

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong column for grouping.

Using sum() instead of n() for counting.

Group by gear, count rows with n(), and average mpg with mean().