tests/testthat/test-backtransform_response.R

In javifar/ggeffects: Create Tidy Data Frames of Marginal Effects for 'ggplot' from Model Outputs

if (require("testthat") && require("ggeffects") && require("emmeans")) {
  reprex <- data.frame(
    time = as.factor(c(1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5)),
    group = c(1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2),
    id = c(10, 10, 10, 10, 10, 15, 15, 15, 15, 15, 20, 20, 20, 20, 20, 25, 25, 25, 25,25, 30, 30, 30, 30, 30, 35, 35, 35, 35, 35),
                     factor1 = as.factor(c(0, 0, 0, 0, 0, 0, 0,0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 0,0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1)),
    factor2 = as.factor(c(1, 1, 1, 1,1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1)),
    score = c(7, 7, 7, 4, 2, 2, 2, 2, 1, 1, 5, 5, 7, 8, 6, 0, 2, 3, 3, 3, 6, 8, 8, 8, 8, 2, 4, 4, 3, 2)
  )

  m1 <-  lm(sqrt(score + 5) ~ as.numeric(time) * group, data = reprex)
  m2 <-  lm(log(score + 1) ~ as.numeric(time) * group, data = reprex)

  test_that("ggpredict-log-response", {
    p1 <- suppressMessages(ggpredict(m1, c("time", "group")))
    p2 <- as.data.frame(emmeans(m1, c("time", "group"), at = list(time = 1:5), type = "response"))
    expect_equal(p1$predicted[1], p2$response[1], tolerance = 1e-3)
    expect_equal(p1$predicted[1], 6.677575, tolerance = 1e-3)
  })

  test_that("ggpredict-sqrt-response", {
    p1 <- suppressMessages(ggpredict(m2, c("time", "group")))
    p2 <- as.data.frame(emmeans(m2, c("time", "group"), at = list(time = 1:5), type = "response"))
    expect_equal(p1$predicted[1], p2$response[1], tolerance = 1e-3)
    expect_equal(p1$predicted[1], 6.743365, tolerance = 1e-3)
  })
}