Running examples in ‘mlr-Ex.R’ failed
The error most likely occurred in:

> base::assign(".ptime", proc.time(), pos = "CheckExEnv")
> ### Name: benchmark
> ### Title: Benchmark experiment for multiple learners and tasks.
> ### Aliases: benchmark
> 
> ### ** Examples
> 
> ## Don't show: 
>  if (requireNamespace("rpart")) { 
+ ## End(Don't show)
+ ## Don't show: 
+  if (requireNamespace("MASS")) { 
+ ## End(Don't show)
+ ## Don't show: 
+  if (requireNamespace("rpart")) { 
+ ## End(Don't show)
+ ## Don't show: 
+  if (requireNamespace("PMCMRplus")) { 
+ ## End(Don't show)
+ lrns = list(makeLearner("classif.lda"), makeLearner("classif.rpart"))
+ tasks = list(iris.task, sonar.task)
+ rdesc = makeResampleDesc("CV", iters = 2L)
+ meas = list(acc, ber)
+ bmr = benchmark(lrns, tasks, rdesc, measures = meas)
+ rmat = convertBMRToRankMatrix(bmr)
+ print(rmat)
+ plotBMRSummary(bmr)
+ plotBMRBoxplots(bmr, ber, style = "violin")
+ plotBMRRanksAsBarChart(bmr, pos = "stack")
+ friedmanTestBMR(bmr)
+ friedmanPostHocTestBMR(bmr, p.value = 0.05)
+ ## Don't show: 
+  } 
+ ## End(Don't show)
+ ## Don't show: 
+  } 
+ ## End(Don't show)
+ ## Don't show: 
+  } 
+ ## End(Don't show)
+ ## Don't show: 
+  } 
Loading required namespace: rpart
Loading required namespace: PMCMRplus
Task: iris-example, Learner: classif.lda
Resampling: cross-validation
Measures:             acc       ber       
[Resample] iter 1:    0.9600000 0.0401235 
[Resample] iter 2:    1.0000000 0.0000000 


Aggregated Result: acc.test.mean=0.9800000,ber.test.mean=0.0200617


Task: Sonar-example, Learner: classif.lda
Resampling: cross-validation
Measures:             acc       ber       
[Resample] iter 1:    0.6538462 0.3470218 
[Resample] iter 2:    0.7211538 0.2972264 


Aggregated Result: acc.test.mean=0.6875000,ber.test.mean=0.3221241


Task: iris-example, Learner: classif.rpart
Resampling: cross-validation
Measures:             acc       ber       
[Resample] iter 1:    0.9333333 0.0679012 
[Resample] iter 2:    0.8400000 0.1555184 


Aggregated Result: acc.test.mean=0.8866667,ber.test.mean=0.1117098


Task: Sonar-example, Learner: classif.rpart
Resampling: cross-validation
Measures:             acc       ber       
[Resample] iter 1:    0.6730769 0.3303737 
[Resample] iter 2:    0.7307692 0.2953523 


Aggregated Result: acc.test.mean=0.7019231,ber.test.mean=0.3128630


Error in `[.data.table`(df, , `:=`("alg.rank", rank(.SD$x, ties.method = ties.method)),  : 
  attempt access index 3/3 in VECTOR_ELT
Calls: convertBMRToRankMatrix -> [ -> [.data.table
Execution halted