
library(testthat)

source("user_code.R")
test_that("joined_df contains only common ids", {
  expect_true(exists("joined_df"), info = "joined_df should exist.")
  expect_true(is.data.frame(joined_df), info = "joined_df should be a data frame.")
  expect_equal(sort(joined_df$id), c(2, 3, 4),
               info = "joined_df should contain only ids present in both df1 and df2.")
})

test_that("final_df includes all columns from joined_df and additional rows", {
  expect_true(exists("final_df"), info = "final_df should exist.")
  expect_true(is.data.frame(final_df), info = "final_df should be a data frame.")
  expect_equal(colnames(final_df), c("id", "value1", "value2"),
               info = "final_df should have columns id, value1, and value2.")
})

test_that("final_df includes additional rows", {
  expect_true(any(final_df$id == 6), info = "final_df should contain a row with id 6.")
  expect_true(any(final_df$id == 7), info = "final_df should contain a row with id 7.")
  expect_true(any(final_df$value1 == "E"), info = "final_df should contain a row with value1 'E'.")
  expect_true(any(final_df$value2 == "U"), info = "final_df should contain a row with value2 'U'.")
})

test_that("final_df structure matches joined_df", {
  expect_equal(colnames(final_df), colnames(joined_df),
               info = "final_df columns should match those of joined_df.")
})

test_main.R

This practical course introduces learners to essential data cleaning and wrangling techniques in R. Through hands-on exercises, students will learn how to handle missing data, transform and recode variables, filter and select relevant data, and prepare datasets for analysis. The course emphasizes using popular R packages such as dplyr and tidyr to streamline and automate data preparation workflows, equipping learners with the foundational skills needed for effective data analysis.

Master the core techniques for cleaning and wrangling data in R using dplyr and tidyr. Each concept is introduced in a theory chapter, followed by a practical challenge.

Challenge: Combining and Joining Data

Solution