Classwork 9

Combining Tables with left_join()

NoteNote

Complete the questions and submit your responses on the corresponding Brightspace page. Fill in every ____. Copy the completed R code into your script and run it after the setup below.

These two small tables contain fictional student and major information. We want to keep every student and add the full name of each student’s major when a matching code exists.

library(dplyr)

students <- data.frame(
  student_id = 101:104,
  student_name = c("Ava", "Ben", "Cora", "Diego"),
  major_code = c("DANL", "BIOL", "DANL", "ART")
)

majors <- data.frame(
  major_code = c("BIOL", "DANL", "ECON"),
  major_name = c("Biology", "Data Analytics", "Economics")
)

students

student_id	student_name	major_code
101	Ava	DANL
102	Ben	BIOL
103	Cora	DANL
104	Diego	ART

majors

major_code	major_name
BIOL	Biology
DANL	Data Analytics
ECON	Economics

The rows appear in different orders. A join matches key values, not row positions.

Question 1

Which table is the main (left) table, which table supplies the major names, and which column is the matching key? Fill in the names below.

• Main (left) table: ____
• Lookup table supplying the major names: ____
• Matching key column: ____

Question 2

Fill in the code to add major_name to the student table. Save the result as students_with_major and display it.

students_with_major <- ____ |>
  ____(____, by = "____")
students_with_major