Modus

aggregation-functions modus

syntax

  • modus(a)
  • modus(a, relation)

definition

description

An attribute might contain multiple most occurring non null values. In these cases, the modus function results in the lowest most occurring non null value, independent from the sequence of the values in the attribute, see also example 2.

applies to

  • attribute a with uint2, uint4, uint8, uint16, uint32 or bool value-type
  • relation with value type of the goup 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 of argument a and relation must match.

performance

  • Without relation: O(n) where n = number of elements in the domain of a. Builds frequency count for each value.
  • With relation: O(n) where n = number of elements in the domain of a. Builds frequency count per group.
  • Memory usage depends on the cardinality of the values unit.

example 1 

parameter<uint32> modusLifeStyleCode                      := modus(City/LifeStyleCode); result = 1
attribute<uint32> modusLifeStyleCodeRegion (RegionDomain) := modus(City/LifeStyleCode, City/Region_rel);
City/LifeStyleCode City/Region_rel
2 0
0 1
1 2
0 1
1 3
1 null
null 3

domain City, nr of rows = 7

modusLifeStyleCode
2
0
1
1
null

domain Region, nr of rows = 5

example 2 

parameter<uint32> modusSeqA := modus(City/SeqA); result = 1
parameter<uint32> modusSeqB := modus(City/SeqB); result = 1
parameter<uint32> modusSeqC := modus(City/SeqC); result = 1
parameter<uint32> modusSeqD := modus(City/SeqD); result = 1
City/LifeStyleCode City/Region_rel
2 0
0 1
1 2
0 1
1 3
1 null
null 3

domain City, nr of rows = 7

modusLifeStyleCode
2
0
1
1
null

domain Region, nr of rows = 5

see also