Get the default measure for a task type, task, task description or a learner. Currently these are:
| classif | mmce |
| regr | mse |
| cluster | db |
| surv | cindex |
| costsens | mcp |
| multilabel | multilabel.hamloss |
getDefaultMeasure(x)([character(1)` | [Task] | [TaskDesc] | [Learner]) Task type, task, task description, learner name, a learner, or a type of learner (e.g. "classif").
[character(1)` | [Task]: R:character(1) [TaskDesc]: R:TaskDesc [Learner]: R:Learner
(Measure).