Creates a new Aggregator
object.
new_aggregator(label, aggregate)
a human readable label
a function with argument ev
that is a list of length
equal to the number of draws with each element itself being a named list.
Each element of this list corresponds to a metric that has been computed.
In particular, given an Evals
object o
,
aggregate
takes as input o@evals[[method_name]]
(which is a
list of the kind just described). The function aggregate should return a
scalar.