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Spatial Query Plugin

The spatialquery Spatial Query plugin allows to make a spatial query (select features) in a target layer with reference to another layer. The functionality is based on the GEOS library and depends on the selected source feature layer.

Possible operators are:

  • Contains
  • Equals
  • Overlap
  • Crosses
  • Intersects
  • Is disjoint
  • Touches
  • Within

Using the plugin

As an example we want to find regions in the Alaska dataset that contain airports. Following steps are necessary:

  1. Start QGIS and load the vector layers regions.shp and airports.shp.
  2. Load the Spatial Query plugin in the Plugin Manager (see Section Loading a QGIS Core Plugin) and click on the spatialquery Spatial Query icon which appears in the QGIS toolbar menu. The plugin dialog appears.
  3. Select layer regions as source layer and airports as reference feature layer.
  4. Select ‘Contains’ as operator and click [Apply].

Now you get a list of feature IDs from the query and you have several options as shown in figure_spatial_query_1.

  • Click on the selectesubsetlayer Create layer with list of items
  • Select an ID from the list and click on selectcreatelayer Create layer with selected
  • Select the ‘Remove from current selection’ in the field And use the result to selectstring.
  • Additionally you can checkbox Zoom to item or display checkbox Log messages.

Figure Spatial Query 1:

../../../_images/spatial_query_sample.png

Spatial Query analysis - regions contain airports nix