Plugins for QGIS I use most often.

All of these can be installed automatically by QGIS. Click on Plugins>Fetch Python Plugins. Then search for the plugin, click on its name, and click Install Plugin. Few plugins require a restart.

  • MMQGIS – Great for working with CSV files; also merges layers (even if they have differing attributes); has various other useful functions, including converting string data to float data. Has Voronoi diagram function (takes a long time to process).
  • fTools – Replicates some of the most basic geographic tools in ArcGIS, like Clip, Dissolve, and Reproject. Can also add X/Y values to point attribute tables that are missing them (if you want latitude/longitude, you must reproject into a coordinate reference system first, like WGS84 [EPSG: 4326]). Unfortunately, there’s little information on what each fTools function does. Below are descriptions:
    • Extract Nodes – Create a point at each intersection of vertices.
    • Basic Statistics – Generate arithmetic statistics for fields, same as statistics function in ArcGIS. Great for quickly understanding the extent of values in a field (especially numeric values), like mean, max, min, standard deviation, and number of unique values.
    • Nearest Neighbour Analysis – More details here.
    • Geoprocessing Tools>Dissolve – Combine features based on a shared attribute. For example, all features with an identical STREET_TYPE be combined into a single feature. For example, all “Avenues” will become one feature and all “Boulevards” will become a second feature. Only works on polygon layers.
    • Descrição em português
  • Table Manager
  • Open Layers – Embed Google, Yahoo, Bing, and OpenStreetMap layers in your map. See my example.