summarise() with group_by() in R Programming - Mini Project: Build & Apply

Summarise Data with group_by() in R

📖 Scenario: You have sales data from a small store. Each sale has a product name and the number of units sold. You want to find out how many units were sold for each product in total.

🎯 Goal: Build a small R script that groups sales by product and calculates the total units sold for each product using group_by() and summarise().

📋 What You'll Learn

Create a data frame called sales with columns product and units with exact values

Create a grouped data frame using group_by() on product

Use summarise() to calculate total units sold per product

Print the summarised data frame

💡 Why This Matters

🌍 Real World

Stores and businesses often need to summarise sales data by product to understand which items sell the most.

💼 Career

Data analysts and scientists use <code>dplyr</code> functions like <code>group_by()</code> and <code>summarise()</code> to prepare and analyse data efficiently.

1

Create the sales data frame

Create a data frame called sales with two columns: product and units. Use these exact values: product = c("apple", "banana", "apple", "orange", "banana"), units = c(5, 3, 2, 4, 1).

R Programming

# Create the sales data frame with product and units columns
# Your code here

Need a hint?

Use data.frame() with named vectors for product and units.

2

Group sales by product

Load the dplyr package with library(dplyr). Then create a new variable called grouped_sales by applying group_by() on the sales data frame grouping by product.

R Programming

sales <- data.frame(
  product = c("apple", "banana", "apple", "orange", "banana"),
  units = c(5, 3, 2, 4, 1)
)

# Load dplyr and group sales by product
# Your code here

Need a hint?

Use library(dplyr) to load the package first.

3

Summarise total units sold per product

Create a new variable called summary_sales by applying summarise() on grouped_sales. Calculate the total units sold per product using total_units = sum(units).

R Programming

library(dplyr)
sales <- data.frame(
  product = c("apple", "banana", "apple", "orange", "banana"),
  units = c(5, 3, 2, 4, 1)
)
grouped_sales <- group_by(sales, product)

# Summarise total units sold per product
# Your code here

Need a hint?

Use summarise() with total_units = sum(units) inside.

4

Print the summarised sales data

Print the summary_sales data frame to show total units sold per product.

R Programming

library(dplyr)
sales <- data.frame(
  product = c("apple", "banana", "apple", "orange", "banana"),
  units = c(5, 3, 2, 4, 1)
)
grouped_sales <- group_by(sales, product)
summary_sales <- summarise(grouped_sales, total_units = sum(units))

# Print the summary_sales data frame
# Your code here

Need a hint?

Use print(summary_sales) to display the result.