The weight every learner that ships fits a presence-absence response under: each presence of a
response weighs the ratio of absences to presences among the units handed in, capped, and each
absence weighs one. A response with a presence in one target of a hundred is otherwise fitted
away by any learner that minimises a mean loss, and the encoders, the penalised fit, the forest
and the forward search would each have to decide that for themselves.
Usage
positive_weights(y, cap = 50)
Arguments
- y
The response matrix, [unit, variable], 0/1.
- cap
Ceiling on the weight a presence is given, at least one.
Value
A numeric [unit, variable] matrix of case weights, one per cell of y.
Details
The weights are the response head's: the shipped presence-absence head carries this function
as its weights, and a head registered with weights = function(y) positive_weights(y, cap = 20) weights every learner by that cap instead. A head without weights is fitted unweighted.
Examples
y <- cbind(rare = c(1, 0, 0, 0, 0, 0), common = c(1, 1, 1, 0, 0, 0))
positive_weights(y)