plNested PerformancecalcNested calculates a single performance measure for the
results of a plNested function call.
calcNested(pl, colBy)ExprsPipeline object returned by plNested.calcNested averages
the validation set performance for the "best" model (where "best" is
defined as the model with the maximum "internal" cross-validation
accuracy, max($train.plCV)). The validation set performance
ultimately averaged depends on the supplied colBy argument.