Cumulate

Arithmetic functions cumulate

syntax

  • cumulate(a)
  • cumulate(a, relation)

definition

  • cumulate(a) results in an Attribute with the cumulation of the non Null values of attribute a.
  • cumulate(a, relation) results in an attribute with the cumulation of the non null values of attribute a, grouped by the relation. The Domain unit of the resulting attribute is the values unit of the relation attribute.

description

  1. For domain units with Index numbers starting from 0 (default), cumulate(const(1, domainunit, uint32)) - 1 is synonym for Id(domain unit). It is advised to use the id function in such a case.
  2. There is no id(domainunit, relation) function, use cumulate(const(1, domainunit, uint32), relation) - 1 to calculate index numbers for each entry in the relation domain.

applies to

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 and relation must match.

Since GeoDMS 20.23.1 a partial sum that does not fit the value type of a is an error, as it is for Sum. Before, it was stored without a check and wrapped: cumulate of a uint8 attribute [200, 100] gave [200, 44], an int32 sum past 2^31 turned negative, and a uint32 partial sum of 4294967295 became Null. A configuration that cumulates into a narrow value type can therefore stop on its first run after upgrading; cumulate a wider value type instead.

since version

6.061

example 

1. attribute<uint32> cumulateNrInh       (City) := cumulate(City/NrInhabitants);
2. attribute<uint32> cumulateNrInhRegion (City) := cumulate(City/NrInhabitants, City/Region_rel);
City/NrInhabitants City/Region_rel cumulateNrInh cumulateNrInhRegion
550 0 550 550
525 1 1075 525
300 2 1375 300
500 1 1875 1025
200 3 2075 200
175 null 2250 null
null 3 2250 200

domain City, nr of rows = 7