Research Article

An Adaptive Heterogeneous Online Learning Ensemble Classifier for Nonstationary Environments

Algorithm 1

HDES-AD algorithm.
Input: Stream of examples and class labels
: set of diverse and accurate learners
: Max size of ensemble
: global and local predictions
(1)For learner = 1 to //loop over learners
(2)For j = 1 to m//loop over instances
(3) = classify ()//classify with dynamic pool
(4)If (i mod  = 0) then
(5)If ()
(6) reset
(7) recalculate
(8)
(9)If ( and ) then
(10) remove I//delete learner with least Accuracy and Diversity
(11)End if Call Active Drift Handler (, )
(12)End for
(13)If (i mode  = 0) then
(14) update accuracy and diversity
(15)If (), then Call Passive Drift handler
(16)End if
(17)If size () = , then
(18)(, ) remove ()min
(19)End if
(20)For i = 1 to
(21)Train (, )
(22)End for
(23)End if