Algorithm 1. Enhanced Reactive Drift Detection Method

Input: stream, n, αw, αd, max, min, warnLimit storedPredictions ← NEW byte [min] reset m_n,m_p,m_s,m_pmin,m_smin,m_psmin rddmDrift ← ddmDrift ← false numInstConcept ← numWarnings ← 0 m_t_array ← [ ] Output: 1. foreach instance in stream do 2.   pred prediction (instance) 3.  If rddmDrift Then 4.   reset m_n,m_p,m_s,m_pmin,m_smin,m_psmin 5.   Calculate DDM statistics using the element of storedPrediction 6.   rddmDrift ← ddmDrift ← false 7.   numInstConcept ← numWarning ← 0 8.  End If 9.  Inserts pred into array storedPredictions forgetting oldest value if it is already full 10. m_p ← m_p + (pred – m_p)/m_n 11. m_s ← sqrt (m p × (1 – m_p)/m_n) 12. m_n ← m_n + 1 13. numInstConcept ← numInstConcept + 1 14. warningLevel ← false 15. If numInstConcept _ n Then 16.   x_avg ← (1/m_n) x m_p 17.  m_t ← (m_s - x_avg) + n 18.  m_t_array.add(m_t) 19.  M_t = min (m_t_array) 20.  If M_t – m_t < m_psmin Then 21.   m_pmin ← m_p; m_smin ← m_s 22.   m_psmin m_p + m_s End If 23. If M_t – m_t > m_pmin + αd × m_smin Then 24.  rddmDrift ← ddmDrift ← true 25.  If numWarnings ← 0 Then 26.   storedPredictions ← pred 27.   End If 28. else If M_t – m_t > m_pmin +αw x s_min Then 29.  If numWarning >= warnLimit Then 30.   rddmDrift ← ddmDrift ← true 31.   storedPredictions ← pred 32.  else 33.   warningLevel ← true 34.   numWarnings ← numWarnings + 1 35.  End If 36. else numWarnings ← 0 37. End If 38. If numInstConcept >= max and not warningLevel Then 39.  rddmDrift ← true 40. End If 41. End For