overlay

Details: Last Updated on Monday, 21 January 2013 16:43

syntax

overlay(a, b, c)

definition

overlay(a, b, c) results in a new uint16 domain unit. A subitem UnionData is generated for this domain unit, containing different index numbers of this domain unit for each unique combination of the occuring values in the source attributes. Attribute a contains the names of the source attributes. These attributes need to be configured in container c. Argument b is the domain unit of the source and the resulting attributes.

description

The overlay function is e.g. used to create unique regions in the discrete allocation function, used in amonst others the Land Use Scanner.

applies to

Attribute a with value type:

string

Domain unit b with value type:

group: CanBeDomainUnit

Tree item c needs to be a container.

conditions

All attributes to be overlayed need to match with regard to their domain unit. Null values are not allowed in the source attributes.

since version

5.51

example

unit<uint8> OverlayRegios: nrofrows = 2
{
   attribute<string> namen: ['NoordZuid', 'OostWest'];
}
container OverlayGrids
{
   attribute<uint8> NoordZuid (GridDomain)
   :  StorageName = "%projdir%/data/overlayNZ.asc";
   attribute<uint8> OostWest  (GridDomain)
   :  StorageName = "%projdir%/data/overlayOW.asc";
}
unit<uint16> NoordZuidOostWest
:  expr = "overlay(OverlayRegios/namen, GridDomain, OverlayGrids)";

NoordZuid:


0	0	0	0	0
0	0	0	0	0
1	1	1	1	1
1	1	1	1	1
1	1	1	1	1

Table GridDomain, nr of rows = 5, nr of cols = 5

OostWest:


0	0	0	1	1
0	0	0	1	1
0	0	0	1	1
0	0	0	1	1
0	0	0	1	1

Table GridDomain, nr of rows = 5, nr of cols = 5

NoordZuidOostWest/UnionData:


0	0	0	2	2
0	0	0	2	2
1	1	1	3	3
1	1	1	3	3
1	1	1	3	3

Table GridDomain, nr of rows = 5, nr of cols = 5