Dear Gene, Maybe my have not been well explained but I don't need the straight cartesian distance but the distance following the line (as a path). I think the code posted by Giovanni should be fine for my case. I will test it right now.
Thanks Pierluigi Il giorno mer, 14/01/2015 alle 00.05 -0800, gene ha scritto: > It is a pure problem of analytical geometry or vector calculus (look at > PyQGIS: geometry, vectors, vector algebra or direction cosines...(in French > <http://www.portailsig.org/content/pyqgis-des-geometries-des-vecteurs-de-l-algebre-vectorielle-ou-des-cosinus-directeurs> > > )) > > Is the line is straight the cartesian distance between two points is given > by > > def distance(point1,point2): > #Theoretical cartesian Euclidean distance between 2 points (x,y) > return math.sqrt((point2.x()-point1.x())**2 + > (point2.y()-point1.y())**2) > > As PyQGIS has the sqrDist function, you can replace by > > def distance(point1,point2): > return math.sqrt(point1.sqrDist(point2)) > > By definition, the point of intersection between two lines lies on the two > lines. It is easy to extract the start point or the end point of the lines > and calculate the distance. > > If you want a confirmation, there are many algorithms in Python to verify > that 3 points are collinear > > If the line has many segments, work at the straight segments level > > > > -- > View this message in context: > http://osgeo-org.1560.x6.nabble.com/calculate-distance-from-two-points-along-line-in-pyqgis-tp5181313p5181376.html > Sent from the Quantum GIS - Developer mailing list archive at Nabble.com. > _______________________________________________ > Qgis-developer mailing list > Qgis-developer@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/qgis-developer -- ________________________________________________________________________ Ing. Pierluigi De Rosa (PhD) Studio Associato GFOSSERVICES Presso CAMPUS Via F.lli Cairoli 25 - 06127 Perugia (PG) fax: 075 7823038 cel: 3497558268 web: www.gfosservices.it skype: pierluigi.derosa _______________________________________________ Qgis-developer mailing list Qgis-developer@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-developer