fix: weights_measure and stratum (#1406)

* fix: weights_measure and stratum

* ...

Author: be-marc

R/as_prediction_data.R

@@ -45,7 +45,7 @@ as_prediction_data.list = function(x, task, row_ids = task$row_ids, check = TRUE
   }
 
   if ("weights_measure" %chin% task$properties) {
-    x$weights = task$weights_measure[list(row_ids), "weight"][[1L]]
+    x$weights = task$weights_measure[list(row_id = row_ids), on = "row_id", "weight"][[1L]]
   }
 
   task = if (task$task_type == "unsupervised") train_task else task

tests/testthat/test_Task.R

@@ -1020,3 +1020,13 @@ test_that("materialize_view works with duplicates", {
   task2$materialize_view()
   expect_equal(task$data(), task2$data())
 })
+
+test_that("weights_measure + stratum works during resampling (#1405)", {
+  data = cbind(datasets::iris, data.frame(w = rep(c(1, 10, 100), each = 50)))
+  # 150 rows works, but 151 rows fails
+  data = data[c(seq(150), 1), ]
+  task = TaskClassif$new("iris_weights_measure", as_data_backend(data, target = "Species"), target = "Species")
+  task$set_col_roles("w", "weights_measure")
+  task$set_col_roles("Species", roles = c("target", "stratum"))
+  expect_resample_result(resample(task, lrn("classif.featureless"), rsmp("cv", folds = 3)))
+})