Accessing columns ($, []) in R Programming - Mini Project: Build & Apply

Accessing columns ($, [])

📖 Scenario: You have a small table of fruits and their prices. You want to get the prices using two common ways in R: the $ operator and the [] operator.

🎯 Goal: Learn how to access columns in a data frame using $ and [] in R.

📋 What You'll Learn

Create a data frame called fruits with columns name and price

Create a variable called col_name with the value "price"

Use the $ operator to get the price column and save it in prices_dollar

Use the [] operator with col_name to get the price column and save it in prices_brackets

Print both prices_dollar and prices_brackets

💡 Why This Matters

🌍 Real World

Accessing columns in data frames is a common task when working with data in R, such as analyzing sales, survey results, or scientific data.

💼 Career

Data analysts and scientists frequently use these techniques to manipulate and explore data sets efficiently.

1

Create the data frame

Create a data frame called fruits with two columns: name containing "apple", "banana", "cherry" and price containing 1.2, 0.5, 2.5.

R Programming

# Your code here

Need a hint?

Use data.frame() with name = c(...) and price = c(...).

2

Create the column name variable

Create a variable called col_name and set it to the string "price".

R Programming

fruits <- data.frame(name = c("apple", "banana", "cherry"), price = c(1.2, 0.5, 2.5))
# Your code here

Need a hint?

Use <- "price" to create the variable.

3

Access the price column using $ and []

Use the $ operator on fruits to get the price column and save it in prices_dollar. Then use the [] operator with col_name on fruits to get the same column and save it in prices_brackets.

R Programming

fruits <- data.frame(name = c("apple", "banana", "cherry"), price = c(1.2, 0.5, 2.5))
col_name <- "price"
# Your code here

Need a hint?

Use fruits$price and fruits[[col_name]].

4

Print the results

Print the variables prices_dollar and prices_brackets to show the prices.

R Programming

fruits <- data.frame(name = c("apple", "banana", "cherry"), price = c(1.2, 0.5, 2.5))
col_name <- "price"
prices_dollar <- fruits$price
prices_brackets <- fruits[[col_name]]
# Your code here

Need a hint?

Use print(prices_dollar) and print(prices_brackets).