select()

This lesson is called select(), part of the Fundamentals of R course. This lesson is called select(), part of the Fundamentals of R course.

Transcript

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# Load Packages -----------------------------------------------------------

library(tidyverse)

# Import Data -------------------------------------------------------------

penguins <-
  read_csv("penguins.csv")

# select() ----------------------------------------------------------------

penguins

# With select() we can select variables from the larger data frame.

penguins |>
  select(bill_length_mm)

# We can also use select() for multiple variables:

penguins |>
  select(bill_length_mm, bill_depth_mm)

# select() has several helper functions for selecting variables.

# The contains() function finds any variable with certain text
# in the variable name:

penguins |>
  select(contains("bill"))

# The starts_with() function allows us to select variables
# that start with certain text:

penguins |>
  select(starts_with("bill"))

# The ends_with() function allows us to select variables that end with certain text:

penguins |>
  select(ends_with("mm"))

# We can select a range of columns using the var1:var2 pattern

penguins |>
  select(species:bill_length_mm)

# We can drop variables using the -var format:

penguins |>
  select(-bill_length_mm)

# We can drop a set of variables using the -(var1:var2) format:

penguins |>
  select(-(bill_length_mm:flipper_length_mm))

Your Turn

Solution

# Load Packages -----------------------------------------------------------

# Load the tidyverse package

library(tidyverse)

# Import Data -------------------------------------------------------------

# Download data from https://rfor.us/penguins
# Copy the data into your Positron project where you downloaded the penguins data
# Overwrite your R code that you created previously with the code below

penguins <- read_csv("penguins.csv")

# select() ----------------------------------------------------------------

# Use select() to keep only the sex variable

penguins |> 
  select(sex)

# Use select() to keep the island and sex variables

penguins |> 
  select(island, sex)

# Use one of the select() helper functions to keep all variables that have the letter s in their names

penguins |> 
  select(contains("s"))

# Use one of the select() helper functions to keep all variables that start with the letter b

penguins |> 
  select(starts_with("b"))

# Use select() to keep the variables from island to the end

penguins |> 
  select(island:year)

# Use the dropping syntax with - to keep the same variables as above (island to the end)

penguins |> 
  select(-species)

# Drop all variables from bill_length_mm to body_mass_g

penguins |> 
  select(-(bill_length_mm:body_mass_g))

Copy the code below into your R script file and complete the exercises.

# Load Packages -----------------------------------------------------------

# Load the tidyverse package

library(tidyverse)

# Import Data -------------------------------------------------------------

# Download data from https://rfor.us/penguins
# Copy the data into your Positron project where you downloaded the penguins data
# Overwrite your R code that you created previously with the code below

penguins <- read_csv("penguins.csv")

# select() ----------------------------------------------------------------

# Use select() to keep only the sex variable

# YOUR CODE HERE

# Use select() to keep the island and sex variables

# YOUR CODE HERE

# Use one of the select() helper functions to keep all variables that have the letter s in their names

# YOUR CODE HERE

# Use one of the select() helper functions to keep all variables that start with the letter b

# YOUR CODE HERE

# Use select() to keep the variables from island to the end

# YOUR CODE HERE

# Use the dropping syntax with - to keep the same variables as above (island to the end)

# YOUR CODE HERE

# Drop all variables from bill_length_mm to body_mass_g
			
# YOUR CODE HERE

Learn More

To learn more about the select() function, check out Chapter 3 of R for Data Science.

Have any questions? Put them below and we will help you out!

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Lilly Yu • September 29, 2026

For the last function where we drop a range of variables, the console still shows me the variables that I dropped: species island bill_length_mm bill_depth_mm flipper_length_mm body_mass_g. Is this correct?

Gracielle Higino Coach • September 30, 2026

Hi Lilly! It depends a bit on what you asked R to show you. The last exercise should still show species, but not bill_length_mm, for example. Can you share your exact code, please?

Lilly Yu • September 30, 2026

I think I figured it out--I had omitted the second parenthesis after the minus sign. Thank you!

Mallik Janthak • October 5, 2026

How do you identify the first column of the data frame without naming it? I was able to use this for the last column in the following exercise.

Use select() to keep the variables from island to the end

penguins |> select(island:last_col())

Gracielle Higino Coach • October 5, 2026

Hi Mallik! I think there's no equivalent to last_col() for the first column because you can use the index of the column for this (select(1)). The first column will always have an index of 1, whereas the last column’s index depends on the number of variables in your dataset, hence the need for a “shortcut.”