
library(testthat)

source("user_code.R")
test_that("subject_medians exists and is correct", {
  expect_true(exists("subject_medians"), info = "subject_medians variable does not exist.")
  expect_true(is.numeric(subject_medians), info = "subject_medians should be numeric.")
  expect_equal(length(subject_medians), 3, info = "subject_medians should have length 3.")
  expected_medians <- c(math = 85, english = 86, science = 89)
  expect_equal(subject_medians["math"], expected_medians["math"], info = "Median for math is incorrect.")
  expect_equal(subject_medians["english"], expected_medians["english"], info = "Median for english is incorrect.")
  expect_equal(subject_medians["science"], expected_medians["science"], info = "Median for science is incorrect.")
})

test_that("group_math_means exists and is correct", {
  expect_true(exists("group_math_means"), info = "group_math_means variable does not exist.")
  expect_true(is.numeric(group_math_means), info = "group_math_means should be numeric.")
  expect_equal(length(group_math_means), 2, info = "group_math_means should have two elements (X and Y).")
  expected_means <- c(X = mean(c(82, 76, 95)), Y = mean(c(91, 88, 79)))
  expect_equal(group_math_means["X"], expected_means["X"], info = "Mean math score for group X is incorrect.")
  expect_equal(group_math_means["Y"], expected_means["Y"], info = "Mean math score for group Y is incorrect.")
})

test_main.R

Master the essentials of control flow in R, including conditional statements, loops, and the powerful apply family of functions. This course is designed for beginners and will guide you through practical, real-world examples to help you write efficient and readable R code.

Learn how to control the flow of your R programs using conditional statements, including if, else, else if, and how to apply logic to vectors.

Master the use of loops in R, including for, while, and repeat, and learn how to optimize your code for efficiency.

Unlock the power of R's apply family functions to perform operations on data structures efficiently and elegantly.

Challenge: Grouped Means with tapply

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