Merging data frames in R Programming - Mini Project: Build & Apply

Merging data frames

📖 Scenario: You work in a small company that keeps customer and order information in separate tables. You want to combine these tables to see which customers made which orders.

🎯 Goal: Build a simple R program that merges two data frames: one with customer details and one with order details, using a common column.

📋 What You'll Learn

Create two data frames with exact given data

Create a variable for the common column name

Use the merge() function with the common column

Print the merged data frame

💡 Why This Matters

🌍 Real World

Combining customer and order data is common in business to analyze sales and customer behavior.

💼 Career

Data analysts and data scientists often merge data from different sources to prepare for analysis and reporting.

1

Create the initial data frames

Create a data frame called customers with columns customer_id and name containing these rows: (1, "Alice"), (2, "Bob"), (3, "Charlie"). Also create a data frame called orders with columns order_id, customer_id, and product containing these rows: (101, 1, "Book"), (102, 2, "Pen"), (103, 1, "Notebook").

R Programming

# Create the customers and orders data frames with the exact data
# Your code here

Need a hint?

Use data.frame() with vectors for each column to create the data frames.

2

Set the common column name

Create a variable called common_col and set it to the string "customer_id" to use as the key for merging.

R Programming

customers <- data.frame(customer_id = c(1, 2, 3), name = c("Alice", "Bob", "Charlie"))
orders <- data.frame(order_id = c(101, 102, 103), customer_id = c(1, 2, 1), product = c("Book", "Pen", "Notebook"))
# Create the variable common_col with value "customer_id"
# Your code here

Need a hint?

Just assign the string "customer_id" to the variable common_col.

3

Merge the data frames

Use the merge() function to merge customers and orders by the column stored in common_col. Save the result in a variable called merged_data.

R Programming

customers <- data.frame(customer_id = c(1, 2, 3), name = c("Alice", "Bob", "Charlie"))
orders <- data.frame(order_id = c(101, 102, 103), customer_id = c(1, 2, 1), product = c("Book", "Pen", "Notebook"))
common_col <- "customer_id"
# Merge customers and orders by common_col into merged_data
# Your code here

Need a hint?

Use merge(customers, orders, by = common_col) to join the tables on the common column.

4

Print the merged data frame

Write a print() statement to display the merged_data data frame.

R Programming

customers <- data.frame(customer_id = c(1, 2, 3), name = c("Alice", "Bob", "Charlie"))
orders <- data.frame(order_id = c(101, 102, 103), customer_id = c(1, 2, 1), product = c("Book", "Pen", "Notebook"))
common_col <- "customer_id"
merged_data <- merge(customers, orders, by = common_col)
# Print the merged_data data frame
# Your code here

Need a hint?

Use print(merged_data) to show the combined table.