Modus_weighted

aggregation-functions modus_weighted

syntax

  • modus_weighted(a, weight)
  • modus_weighted(a, weight, relation)

definition

  • modus_weighted(a, weight) results in the parameter with the value of attribute a for the maximum sum of the values of the weight attribute.
  • modus_weighted(a, weight, relation) results in an attribute with the values of attribute a for the maximum sum of the values of the weight attribute, grouped by relation. The domain-unit of the resulting attribute is the values-unit of the relation.

applies to

  • attribute a with uint2, uint4, uint8, uint16, uint32 or bool value-type
  • attribute weight with Numeric value type
  • relation with value type of the group CanBeDomainUnit

conditions

  1. The values unit of the resulting data-item should match with regard to value type and metric with the values unit of attribute a.
  2. The domain unit of arguments a, weight and relation must match.

performance

  • Without relation: O(n) where n = number of elements. Accumulates weighted sums for each unique value of a.
  • With relation: O(n) where n = number of elements. Accumulates weighted sums per group.
  • Memory usage depends on the cardinality of the values unit of a.

example 

1. parameter<uint32> modus_wLifeStyleCode                := 
    modus_weighted(City/LifeStyleCode, City/NrInhabitants); result = 0
2. attribute<uint32> modus_wLifeStyleCodeRegion (Region) :=
    modus_weighted(
       City/LifeStyleCode
     , City/NrInhabitants
     , City/Region_rel
  );
City/LifeStyleCode City/NrInhabitants City/Region_rel
2 550 0
0 525 1
1 300 2
0 500 1
1 200 3
1 175 null
null null 3

domain City, nr of rows = 7

modus_wLifeStyleCode
2
0
1
1
null

domain Region, nr of rows = 5

see also