Nth_element_weighted

aggregation-functions nth_element_weighted

syntax

• nth_element_weighted(rank, targetweight, weight)
• nth_element_weighted(rank, targetweight, weight, relation)

definition

• nth_element_weighted(rank, targetweight, weight) results in a parameter with a rank value. To calculate this rank value, first the sort order of the weight argument is determined by sorting the rank attribute ascending. The weight values are now cumulated according to this sort order until the value of the parameter with the targetweight is reached. The rank value for this element is the result of the nth_element_weighted function.
• nth_element_weighted(rank, targetweight, weight, relation) results in an attribute with rank values, calculated as described above, grouped by relation. The domain-unit of the resulting attribute is the values unit of the relation.

applies to

• attribute rank with Numeric value-type data-item
• attribute targetweight with float32 or float64 value type
• attribute weight with float32 or float64 value type
• relation with value type of the group CanBeDomainUnit

conditions

• The values-unit of the arguments targetweight and weight must match and only contain positive values.
• The domain unit of the arguments rank, weight and relation must match.
• In variant 2 the domain of the targetweight argument must match with the domain of the values-unit of the relation (literals or parameters can be used as data items of any domain).

since version

5.95

example

1. parameter<uint32> nth_element_weighted_NrInh :=
   nth_element_weighted(
       City/Ranking
      ,1800f
      ,float32(City/nrInhabitants)
   ); result = 9

2. attribute<float32> nth_element_weighted_NrInhRegion (Region) := 
   nth_element_weighted(
       City/Ranking
      ,400f
      ,float32(City/nrInhabitants)
      ,City/Region_rel
    );

domain City, nr of rows = 7

domain Region, nr of rows = 5

see also

• nth_element
• rth_element