Sequence2points

syntax

sequence2points(arc_polygon_data_item)

definition

sequence2points(arc_polygon_data_item) results in a new Domain unit with all points from the arcs/polygons of the arc_polygon_data_item

The function generates three subitems:

point: a Data item with the points of all arcs/polygons of the arc_polygon_data_item
sequence_rel: a relation towards the domain unit of the arc_polygon_data_item. It is not generated when that domain unit is void, as for a Parameter.
ordinal: a uint32 data item with the order of each point in the arc_polygon_data_item

They are the arguments that Points2sequence takes to build the arcs/polygons again: points2sequence(RoadPointSet/point, RoadPointSet/sequence_rel, RoadPointSet/ordinal) for the example below.

Since GeoDMS 18.0.2 the relation is only available as sequence_rel. Before GeoDMS 8.9.0 it was called SequenceNr, and up to 18.0.1 that name still worked next to sequence_rel. A configuration that refers to .../SequenceNr now fails with Unknown identifier; replace it with sequence_rel.

Names are case insensitive, so Point, Sequence_rel and Ordinal resolve as well, but the engine records these three in lower case, so another spelling is reported as a case mix-up in the event log.

applies to

data item arc_polygon_data_item with fpoint or dpoint Value type and composition type arc or polygon.

performance

O(n) where n = total number of points across all arcs/polygons. Single pass extracting points and building relations.

example

unit<uint32> RoadPointSet := sequence2points(road/geometry);

road/geometry
{2: xy(112631; 399246) xy(111866; 398599)}
{3: xy(111866; 398599) xy(111924; 399495) xy(111524; 401801)}
{2: xy(114921; 401529) xy(114823; 398584)}

domain Road, nr of rows = 3

point	sequence_rel	ordinal
xy(112631; 399246)	0	0
xy(111866; 398599)	0	1
xy(111866; 398599)	1	0
xy(111924; 399495)	1	1
xy(111524; 401801)	1	2
xy(114921; 401529)	2	0
xy(114823; 398584)	2	1

domain RoadPointSet, nr of rows = 7