tests/testthat/test_base_imbal_overbagging.R

In guillermozbta/mir: Machine Learning in R

context("overbagging")

test_that("OverBagging wrapper",  {
  rdesc = makeResampleDesc("CV", iters = 2)
  lrn1 = makeLearner("classif.rpart")
  lrn2 = makeOverBaggingWrapper(lrn1, obw.rate = 2)
  r = resample(lrn2, binaryclass.task, rdesc)
  expect_true(!is.na(r$aggr))
})

test_that("OverBagging wrapper arg check works", {
  task = makeClassifTask(data = binaryclass.df, target = binaryclass.target)
  lrn1 = makeLearner("classif.rpart")
  expect_error(makeOverBaggingWrapper(lrn1, obw.rate = 0.5))
})

test_that("oversampling in each bag works", {
   y = binaryclass.df[, binaryclass.target]
   tab1 = table(y)
   task = makeClassifTask(data = binaryclass.df, target = binaryclass.target)
   lrn1 = makeLearner("classif.rpart")
   lrn2 = makeOverBaggingWrapper(lrn1, obw.rate = 5, obw.iters = 3)
   mod = train(lrn2, task)
   models = getLearnerModel(mod)

   # check min class size gets increased by rate/factor 5
   tab = lapply(seq_along(models), function(i) {
     data = getTaskData(task, models[[i]]$subset)
     tab = table(data[, binaryclass.target])
     expect_equal(tab1["M"], tab["M"])
     expect_equal(tab1["R"], round(tab["R"] / 5))
   })
})

test_that("oversampling bigger class works", {
   y = binaryclass.df[, binaryclass.target]
   z = getMinMaxClass(y)
   tab1 = table(y)
   task = makeClassifTask(data = binaryclass.df, target = binaryclass.target)
   lrn1 = makeLearner("classif.rpart")
   lrn2 = makeOverBaggingWrapper(lrn1, obw.rate = 5, obw.iters = 3, obw.cl = z$max.name)
   mod = train(lrn2, task)
   models = getLearnerModel(mod)

   tab = lapply(seq_along(models), function(i) {
     data = getTaskData(task, models[[1]]$subset)
     tab = table(data[, binaryclass.target])
     expect_equal(tab1["R"], tab["R"])
     expect_equal(tab1["M"], round(tab["M"] / 5))
   })
})