Meaning of Construction / Improvement

[Bernd Welter]

In the official API documentation of xCluster 1 we mention the terms construction and improvement but we do not explain them in detail. Here’s at least a short description of these mechanisms and some more info you can benefit from:

First of all let me mention that a cluster planning tries to satisfy several goals:

• Geographic compactness of the cluster areas
• Balanced workload within the clusters (aka distribution)

Sometimes the satisfaction of one goal means to sacrifice the quality of the alternative goal.

The overall process of a cluster planning is splitted into different phases:

• ConstructionPhase – during this phase the focus is on compact areas. The workload balance is ignored during this phase. We recommend to execute this phase whenever you perform a new clustering.
• ImprovementPhase – during this phase the algorithm tries to improve a given solution by swapping visits between clusters. Compactness and Workload are goals during this phase.
• PostOpt – this special phase tries to improve the compactness again by swapping orders with equal “workload” between the clusters. Furthermore this only affects elements with a single visit during the planning cycle. This means that the distribution of the clusters doesn’t change (because of the “same workload” restriction)

Now within the improvement phase it is possible to specify how strong the two goals are supposed to be considered. Use improvementCompactnessFactor and improvementDistributionFactor to control whether you prefer compactness or distribution. A value of 0 for one of the goals means “not relevant”. The higher the value is the more important it becomes. Here are some examples:

• Distribution does not matter? improvementCompactnessFactor = 100 , improvementDistributionFactor = 0
• Compactness and distribution should be treated almost equal? improvementCompactnessFactor = 100 , improvementDistributionFactor = 100
• Prio A is compactness but also distribution should at least be taken into consideration as a Prio B goal:
  improvementCompactnessFactor = 100 , improvementDistributionFactor = 10