This measure returns the number of observations in the Prediction object.
Its main purpose is debugging.
The parameter na_ratio (numeric(1)) controls the ratio of scores which randomly
are set to NA, between 0 (default) and 1.
Package mlr3measures for the scoring functions.
Dictionary of Measures: mlr_measuresas.data.table(mlr_measures) for a table of available Measures in the running session (depending on the loaded packages).
Extension packages for additional task types:
mlr3proba for probabilistic supervised regression and survival analysis.