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Union data

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Relational functions union_data

Contents

syntax

definition

union_data(domainunit, a, b, .. n) results in a new attribute with as domain unit the first argument: domainunit.

The resulting attribute contains the values of the data items a, b, .., n.

description

The first argument domainunit, is often made with the union_unit function.

The union_data function results in an attribute with as values unit the values units of data items a, b, ..n and as domain unit the first argument of the function (domainunit).

union_data(newdomain, att_old_domain) can be used to convert attributes from a source to a target domain unit.

applies to

conditions

since version

5.15

example

unit<uint32> HollandCity := union_unit(NHCity, ZHCity)
{ 
   attribute<string> name := union_data(., NHCity/name, ZH/City/name); 
}
HollandCity/name
Amsterdam
Haarlem
Alkmaar
Rotterdam
DenHaag
Leiden
Dordrecht
Leiden

domain HollandCity, nr of rows = 8

NHCity/name
Amsterdam
Haarlem
Alkmaar

domain NHCity, nr of rows = 3

ZHCity/name
Rotterdam
DenHaag
Leiden
Dordrecht
Leiden

domain ZHCity, nr of rows = 5

see also

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