Hi all, two days ago I wrote a similar plugin for a LD talk in Pisa. I was unaware of the QgsSpatialIndex class (seems there's no documentation about it in the online QGis API pages or maybe I missed it) so I wrote a simple loop to find the closest feature.
Now I tried also the Nearest plugin and they are different behavior! See the scheenshots [1] [2]. AFAICS, Nearest select a wrong polygon. I see the plugin's code and I think it could a QgsSpatialIndex bug, but it could be also the normal behaviour (I didn't found its documentation on the API pages so I don't know). I'm going to add my plugin (ClosestFeatureFinded) to the Faunalia repo so you can try it and check the different behavior. I hope this can help to find the bug (if any). If you confirm it, I'll fill a bug report. Cheers. [1] http://img87.imageshack.us/img87/3232/nearest.jpg [2] http://img64.imageshack.us/img64/2066/closest.jpg On Fri, Oct 22, 2010 at 9:19 AM, Ziegler Stefan <stefan.zieg...@bd.so.ch>wrote: > there is some strange behaviour when using it with polygon features (at > least I think it's a bit strange): sometimes when you click into a polygon I > would expect that it selects the polygon I clicked into but it selects an > adjacent polygon. This is probably due to the nearestNeighbor method of the > spatial index. Since the two neighboring polygons share a common border the > distance would be equal but the spatial index does not check if the > coordindates of the mouse click lies within one of the two polygons. > > regards > Stefan > > mit freundlichem Gruss > Stefan Ziegler > > > ----- Originalnachricht ----- > Von: "Jim Hammack" <hamm...@gotslack.org> > Gesendet: Don, 21.10.2010 19:20 > An: "Ziegler Stefan" <stefan.zieg...@bd.so.ch> > Cc: qgis-user <qgis-user@lists.osgeo.org> > Betreff: Re: AW: Re: Fwd: [Qgis-user] QGIS "Near" > > > Stefan, > > > > I was looking for the same functionality as Zoran so have > also been working with your "Nearest" plugin. It is exactly > what I need and seems to work well. > > > > Thanks! > > Jim > > > > On 10/20/2010 01:54 PM, Ziegler Stefan wrote: > > > Hi Zoran > > > > I had some time left, took all > my code snippets and also the one from Carson. Please try > the plugin "Nearest" that should cover your example 1: > > > > http://www.catais.org/qgis/plugins.xml > > > > regards > > Stefan > > > -----Ursprüngliche > Nachricht----- > > Von: Zoran Jankovic [mailto:zoran.janko...@zisis.hr] > > Gesendet am: Mittwoch, 20. Oktober 2010 19:21 > > An: qgis-user > > Betreff: Re: Fwd: [Qgis-user] QGIS "Near" > > > > Hi Joe, > > > > > > > On Wed, Oct 20, 2010 at 5:06 PM, Joe > Larson <joela...@gmail.com> > wrote: > > > Does the function 'snapWithContext' > > > http://doc.qgis.org/head/classQgsVectorLayer.html#733b974dce13d587e05cf3d4fc24f208 > > which "Snaps to segment or vertex within given tolerance." > seem like > > what you're looking for? I came across it while trying to > get Quantum > > Navigator working recently...seemed relative, but I'm no > expert! > > > > > > > > This is similar to the mentioned solution with > selecting by radius, or changing the tolerance of ID tool. > Close, but no cigar. Since this is not very urgent, I've > decided to continue pursuing that outlined solution Carson > gave, and write a plugin i Python based on that. Since I > actually never used Python before, it may take a while, > but hey, I get to learn sth. new :-). > > I never got the word back from Carson, has he developed > anything along these lines, but I have to presume he > didn't... > > Anyone interested in joning me, or even earning some > money, is still invited to jump on board. My GIS > implementation project is well on the way, and it seems > there'll even be some money involved :-). > > > > Zoran > > > > > > ~joe > > > > On Tue, Oct 19, 2010 at 9:55 AM, Andreas Neumann > <a.neumann at carto.net>wrote: > > > > > > Hi Zoran, > > > > > > I believe the infrastructure of what you want is > already wihtin the > > > selection and identify tools in QGIS. Isn't this > almost implemented in the > > > current identify tool? > > > > > > > > It sort of is, but not completely. Identify will ID > all the features within > > certain radios (percentage of extent), but it will ID > _all_ of the features > > within this radius. I only need the nearest, no matter > how far away... Let > > us say it is, for simplicity, within current extent. > > > > > > > The current identify tool selects "near" or > "close by" features within a > > > certain tolerance. This tolerance can be set in > "Options" --> "Map tools" > > > "search radius". I believe it currently only > effects the identify tool. Do > > > you want the same tolerance also be used for the > click-selection tool? > > > > > > > > Look above. This could be useful, but it is not the > functionality I'm > > currently looking after. > > > > > > > Are you also aware that in QGIS 1.6 there are new > selection tools? > > > > > > * by click > > > * by rectangle > > > * by polygon > > > * by freehand > > > * by radius > > > > > > > > Yup, these are great, but they all select _multiple_ > features within radius, > > rectangle, etc. > > > > > > > Maybe this also helps to address your needs? > > > > > > Of course you can combine it with previous > selections by pressing the ctrl > > > key. > > > > > > > > > > BR, > > > > > > --- > > Zoran Jankovic > > ZIS-Izrada softvera i savjetovanje / ZIS - Software > Development and > > Consulting > > > > http://www.zisis.hr > > > > M: 00 385 98 682 902 > > T: 00 385 44 683 374 > > > > A. Senoe 4 > > 44320 Kutina > > Croatia > > > > > _______________________________________________ > > Qgis-user mailing list > > Qgis-user@lists.osgeo.org > > http://lists.osgeo.org/mailman/listinfo/qgis-user > > > > > > > > > > > > > > _______________________________________________ > Qgis-user mailing list > Qgis-user@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/qgis-user > > > > _______________________________________________ > Qgis-user mailing list > Qgis-user@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/qgis-user > -- Giuseppe Sucameli
_______________________________________________ Qgis-user mailing list Qgis-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-user