tests/testthat/test_08_predict.R

In ndphillips/FFTrees: Generate, Visualise, and Evaluate Fast-and-Frugal Decision Trees

context("Predict FFT results for new data")


test_that("Can use predict.FFTrees() for an FFTrees object", {

  # Create FFTrees object x:
  data_train <- heart.train
  data_test  <- heart.test

  x <- FFTrees(diagnosis ~ .,
    data = data_train,
    quiet = TRUE
  )

  # Predictions for data_test:
  class_test_pred <- predict(x, newdata = data_test)
  prob_test_pred  <- predict(x, newdata = data_test, type = "prob")
  both_test_pred  <- predict(x, newdata = data_test, type = "both")

  # Raw predictions are a logical vector:
  testthat::expect_type(class_test_pred, type = "logical")

  # Raw predictions have same length as heart.test:
  testthat::expect_length(class_test_pred, nrow(data_test))
  testthat::expect_equal(nrow(prob_test_pred), nrow(data_test))

  # Cases predicted TRUE have higher overall probability than those predicted FALSE:
  out <- aggregate(prob_1 ~ class, FUN = mean, data = both_test_pred)
  testthat::expect_true(out$prob_1[out$class == TRUE] > out$prob_1[out$class == FALSE])

  # No variation in class outcomes when prob_1 is the same
  out <- aggregate(class ~ prob_1, FUN = sd, data = both_test_pred)
  testthat::expect_true(all(out$class == 0))

})


# eof.