Selection — Operator family

Selection Operators keep some features and drop the rest. They are where definitions become data: “larger woodlands” becomes woodland polygons of at least 5 ha, “hedges” becomes GeoDanmark hedges of type Levende.

Part of the Operators families. Used in: Nature content layer (Task), Network gaps and stepping stones (Task).

Selection by attribute

Operator Schema: keeps the features whose attributes (or computed values such as area or length) meet a condition.

Choices to record: the condition and the reason for it; what the condition leaves out (features with an empty or unknown value are a data-quality question, not a detail).

Tools: QGIS Extract by expression (Tool - QGIS). Interactive Select by expression does the same on screen, without a new layer.

Selection by location

Operator Schema: keeps the features of one layer that stand in a spatial relation to another layer: intersect, are within, contain, touch, are disjoint.

Choices to record: the relation, and its direction. Intersect includes features that only touch the edge; are within does not. See Spatial relations.

Tools: QGIS Extract by location (Vector selection).