select_with_attr_by_org_rel
selection-functions select_with_attr_by_org_rel
syntax
- select_with_attr_by_org_rel(src_tree_item, condition)
- select_uint8_with_attr_by_org_rel(src_tree_item, condition)
- select_uint16_with_attr_by_org_rel(src_tree_item, condition)
- select_uint32_with_attr_by_org_rel(src_tree_item, condition)
- select_uint64_with_attr_by_org_rel(src_tree_item, condition)
definition
select_with_attr_by_org_rel(src_tree_item, condition) results in a new domain-unit with a relation to the entries of the domain unit of the condition argument, for which the values of the condition argument are true. Additionally, all subitems from the src_tree_item argument with the same domain unit as the condition become subitems of the resulting select_with_attr_by_org_rel unit and with this resulting unit as new domain unit. The only exception is if the src_tree_item contains an org_rel subitem, this subitem is not added as it would be ambiguous with the new resulting org_rel attribute.
The resulting value-type of the domain unit is derived from the domain unit of the condition argument:
- uint32 for conditions with uint32, boolean, spoint or wpoint value-type
- uint8 for conditions with uint8 value type
- uint16 for conditions with uint16 value type
- uint64 for conditions with uint64, ipoint or upoint value type
The explicit select_uint8_with_attr_by_org_rel, select_uint16_with_attr_by_org_rel, select_uint32_with_attr_by_org_rel and select_uint64_with_attr_by_org_rel functions can be used in the same manner as the select_with_attr_by_org_rel function, to create a new domain unit with the explicit value type.
Between versions 8.6.0 and 8.7.2 the name select_afew was used for the select_with_attr_by_org_rel function.
description
The select_with_attr_by_org_rel function generates a subitem, named org_rel. This data-item contains the relation towards the domain unit of the condition argument.
The select_with_attr_by_org_rel function is efficient for small selections, think about selection with less than 3% of the entries of the original domain. For larger selections, the select_with_attr_by_cond function is advised.
The org_rel data-item can be used in a lookup function to relate attributes to the new domain unit.
See this overview for when to choose which selection operator is feasable.
applies to
- condition must be a boolean attribute or subexpression resulting in boolean values.
since version
8.8.0
example
unit<uint32> City: StorageName = "city.csv", StorageType = "gdal.vect", StoragReadOnly = "True"
{
attribute<string> name
attribute<uint32> RegionCode;
}
unit<uint32> ZHCities := select_with_attr_by_org_rel(City, City/RegionCode == 200)
| City/RegionCode | City/Name |
|---|---|
| 100 | Amsterdam |
| 200 | Rotterdam |
| 300 | Utrecht |
| 200 | Den Haag |
| 400 | Eindhoven |
| null | Haarlem |
| 400 | Tilburg |
domain City, nr of rows = 7
| ZHCities/name | ZHCities/regionCode | ZHCities/org_rel |
|---|---|---|
| Rotterdam | 200 | 1 |
| Den Haag | 200 | 3 |
domain ZHCities, nr of rows = 2
The subitems: name, regionCode and org_rel are generated by the configured select_with_attr_by_org_rel function.