read.csv and write.csv in R Programming - Mini Project: Build & Apply

Reading and Writing CSV Files in R

📖 Scenario: You work in a small shop and keep track of your sales data in a CSV file. You want to load this data into R, make some changes, and then save the updated data back to a new CSV file.

🎯 Goal: Learn how to use read.csv to load data from a CSV file and write.csv to save data back to a CSV file in R.

📋 What You'll Learn

Create a CSV file named sales.csv with given data

Use read.csv to load the CSV file into a variable

Add a new column to the data frame

Use write.csv to save the updated data to a new CSV file

💡 Why This Matters

🌍 Real World

CSV files are a common way to store and share data like sales, inventory, or survey results. Being able to read and write CSV files lets you work with data easily in R.

💼 Career

Many jobs in data analysis, business, and science require handling CSV files. Knowing how to use read.csv and write.csv is a basic but important skill.

1

Create the CSV file sales.csv

Create a CSV file named sales.csv with these exact contents (including header):
Product,Quantity,Price
Apple,10,0.5
Banana,5,0.3
Cherry,20,0.2

R Programming

# Create the CSV file sales.csv with the exact data
# Your code here

Need a hint?

Use write.csv with row.names = FALSE to create the file.

2

Load the CSV file into a variable

Use read.csv to read the file sales.csv into a variable called sales_data.

R Programming

write.csv(data.frame(Product=c("Apple", "Banana", "Cherry"), Quantity=c(10, 5, 20), Price=c(0.5, 0.3, 0.2)), file = "sales.csv", row.names = FALSE)
# Use read.csv to load sales.csv into sales_data
# Your code here

Need a hint?

Use sales_data <- read.csv("sales.csv") to load the data.

3

Add a new column to the data frame

Add a new column called Total to sales_data that multiplies Quantity by Price.

R Programming

write.csv(data.frame(Product=c("Apple", "Banana", "Cherry"), Quantity=c(10, 5, 20), Price=c(0.5, 0.3, 0.2)), file = "sales.csv", row.names = FALSE)
sales_data <- read.csv("sales.csv")
# Add a new column Total to sales_data
# Your code here

Need a hint?

Use sales_data$Total <- sales_data$Quantity * sales_data$Price to create the new column.

4

Save the updated data to a new CSV file

Use write.csv to save sales_data to a new file called updated_sales.csv without row names. Then print the contents of sales_data.

R Programming

write.csv(data.frame(Product=c("Apple", "Banana", "Cherry"), Quantity=c(10, 5, 20), Price=c(0.5, 0.3, 0.2)), file = "sales.csv", row.names = FALSE)
sales_data <- read.csv("sales.csv")
sales_data$Total <- sales_data$Quantity * sales_data$Price
# Save sales_data to updated_sales.csv without row names
# Print sales_data
# Your code here

Need a hint?

Use write.csv(sales_data, file = "updated_sales.csv", row.names = FALSE) and print(sales_data).