QGIS NNPlugin

The QGIS NNPlugin can be used to join two vector layers (the input and the join layer).

A feature from the input layer is joined to the nearest feature in the join layer.

The result of the join is a new vector layer with the same geometry type and coordinate reference system as the input layer.

The result layer will contain all the attributes of both the input and join layers plus a new attribute "distance" that contains the distance between the joined features. The attributes from the join layer will get a prefix ("join_").

The implementation is naive, in that it loops through all the features of the input dataset, and for each feature finds the nearest neighbour in the join dataset. For point input layers, a spatial index is used to speed up the search for neighbours. For line and polygon layers, the geometry of each feature in the input layer is compared to the geometries of all the features of the join layer!

Below is a table that cross tabulates input layer (rows) and join layer (column) geometry types, and indicates the usefulness of the plugin (OK or slow).