Apply family vs loops in R Programming - Hands-On Comparison

Apply Family Functions vs Loops in R

📖 Scenario: You work in a small bakery that tracks daily sales of different bread types. You want to calculate the total sales for each bread type over a week.

🎯 Goal: Build a program that calculates total weekly sales for each bread type using both a for loop and the lapply function, then compare the results.

📋 What You'll Learn

Create a list called daily_sales with 3 named numeric vectors representing sales for 'Sourdough', 'Baguette', and 'Rye' over 7 days

Create a numeric vector called total_sales_loop to store total sales for each bread type using a for loop

Create a numeric vector called total_sales_apply to store total sales for each bread type using lapply

Print both total_sales_loop and total_sales_apply to compare results

💡 Why This Matters

🌍 Real World

Bakeries and small shops often track daily sales data and need to summarize totals quickly to understand performance.

💼 Career

Knowing how to use loops and apply functions in R is essential for data analysts and anyone working with data summaries in real-world business settings.

1

Create the daily sales data

Create a list called daily_sales with these exact entries: Sourdough as c(10, 12, 11, 9, 13, 10, 14), Baguette as c(8, 7, 9, 6, 7, 8, 7), and Rye as c(5, 6, 5, 7, 6, 5, 6).

R Programming

# Create the list daily_sales with sales for Sourdough, Baguette, and Rye
# Your code here

Need a hint?

Use the list() function with named vectors for each bread type.

2

Set up a vector to store totals from the loop

Create a numeric vector called total_sales_loop with length 3 and names matching the names of daily_sales.

R Programming

daily_sales <- list(
  Sourdough = c(10, 12, 11, 9, 13, 10, 14),
  Baguette = c(8, 7, 9, 6, 7, 8, 7),
  Rye = c(5, 6, 5, 7, 6, 5, 6)
)
# Create total_sales_loop vector with length 3 and names from daily_sales
# Your code here

Need a hint?

Use numeric() to create a vector of zeros and names() to assign names.

3

Calculate totals using a for loop and lapply

Use a for loop with variable bread to iterate over names(daily_sales) and sum each bread's sales into total_sales_loop[bread]. Then create total_sales_apply by applying sum to each element of daily_sales using lapply and unlist the result.

R Programming

daily_sales <- list(
  Sourdough = c(10, 12, 11, 9, 13, 10, 14),
  Baguette = c(8, 7, 9, 6, 7, 8, 7),
  Rye = c(5, 6, 5, 7, 6, 5, 6)
)
total_sales_loop <- numeric(length(daily_sales))
names(total_sales_loop) <- names(daily_sales)
# Use a for loop to sum sales into total_sales_loop
# Use lapply with sum on daily_sales and unlist to create total_sales_apply
# Your code here

Need a hint?

Use for (bread in names(daily_sales)) and sum() inside the loop. Use lapply(daily_sales, sum) and unlist() for the apply method.

4

Print the total sales vectors

Print total_sales_loop and total_sales_apply to display the total weekly sales for each bread type.

R Programming

daily_sales <- list(
  Sourdough = c(10, 12, 11, 9, 13, 10, 14),
  Baguette = c(8, 7, 9, 6, 7, 8, 7),
  Rye = c(5, 6, 5, 7, 6, 5, 6)
)
total_sales_loop <- numeric(length(daily_sales))
names(total_sales_loop) <- names(daily_sales)
for (bread in names(daily_sales)) {
  total_sales_loop[bread] <- sum(daily_sales[[bread]])
}
total_sales_apply <- unlist(lapply(daily_sales, sum))
# Print total_sales_loop and total_sales_apply
# Your code here

Need a hint?

Use print(total_sales_loop) and print(total_sales_apply) to show the results.