It comes with QGIS, as long as you installed python support (default on most things, except some Linux platforms). To activate it enable the ftools plugin in the plugin manager. FYI there should also be options in the Processing Toolbox.
I will also take this moment to note, that Centroid will not ensure your point is always inside the polygon (Think quarter moon shapes, or multi polygons). There is a function in Spatialite, Postgis, etc, called Point on Surface that ensures you get a centroid like point that is guaranteed to be inside the polygon. Enjoy, Alex On 02/08/2016 10:54 AM, rsweeny wrote: > Brent > So kind of you to respond. I am afraid "geometry tools" is not an option > on my Vector pull down menu or toolbar. Do I need a plug-in? > I quite agree with you about the centrality of a proper relational > database underpinning the gis. It is getting from one to the other that > is giving me the headaches. > Robert > > On 08/02/2016 7:01 PM, Brent Wood wrote: >> Hi Robert, >> >> You can create a layer of points for each polygon using:Vector - >> Geometry Tools - Polygon Centroids >> >> if you have a common field in this and the census data, you can then >> join the two: >> Layer - Properties - Join >> >> But I recommend the use of an underlying database tool to manage your >> data, such as Postgis or Spatiallite, and join the data there to be >> used in QGIS. A collection of files does not provide the power of a >> database for managing data, even when accessed by QGIS. >> >> Well managed data is the foundation your analysis, model or GIS sits >> on... >> >> Cheers >> >> Brent Wood >> ------------------------------------------------------------------------ >> *From:* rsweeny <rswe...@mun.ca> >> *To:* qgis-user@lists.osgeo.org >> *Sent:* Tuesday, February 9, 2016 2:10 AM >> *Subject:* [Qgis-user] adding points within polygons >> >> Hi >> People's answers to Grant's question were so clear I'm hoping that >> something similar might exist to facilitate my task. I have 32k of >> polygons representing every lot in the city of Montreal in 1903. I also >> have the 1901 census returns coded by household (95k of them) to those >> lots. Is there a simple way to have Qgis place points within each lot >> polygon for the corresponding households? >> Thanks in advance. >> Robert >> >> -- >> Robert C.H. Sweeny >> Professor of History >> Memorial University of Newfoundland >> St John's NL, A1C 5S7 >> Canada >> 709-864-8440, 709-864-2164 (fax) >> >> _______________________________________________ >> Qgis-user mailing list >> Qgis-user@lists.osgeo.org <mailto:Qgis-user@lists.osgeo.org> >> List info: http://lists.osgeo.org/mailman/listinfo/qgis-user >> Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user >> > > > > _______________________________________________ > Qgis-user mailing list > Qgis-user@lists.osgeo.org > List info: http://lists.osgeo.org/mailman/listinfo/qgis-user > Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user > _______________________________________________ Qgis-user mailing list Qgis-user@lists.osgeo.org List info: http://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user
