Hi Larry, probably I don't understand well the concept of "at geos level".
My english is worsened ultimately. :( I understand that Giovanni say to add some change to geos library , to change the methods or adding some new method in the geos. :) I agree that the solution is to add to qgis the capability to receive a collection and extract a basic type (simple o multi point,line,poly) from it. Regards, A. 2014-07-05 20:52 GMT+02:00 Larry Shaffer <[email protected]>: > HI, > > > On Sat, Jul 5, 2014 at 12:10 PM, Andrea Peri <[email protected]> wrote: >> >> Is wrong. >> The geos return a collection when the collectionis the right result. >> >> if the result is a collection like: >> collection (multipolygons, multilinestrings, multipoint) >> >> why it should remove the lines and points. >> >> It could be useful to the client. >> The fact that the client is capable to understand only point/line and >> polgons is a problem of the client , not of the geos. >> >> If the invoker is not capable to understand collection, but it want do >> operation that could return collection. >> The invoker (the client) should increase him matematics capability , >> not decrease the capability of geos. >> :) >> >> In postgis and spalite is easy manage this kind of situation even if >> the table is not a collection. >> >> With a "ExtractFromCollection(ForceToCollection(geometry)..)" >> you can easily to resolve the problem on postgis/spatialite. > > > > I fail to see how Giovanni is 'wrong' here. Unless I am incorrect, he is > suggesting that QGIS do exactly the same thing, i.e. implement something > like ExtractFromCollection() where needed, when the geometry is converted > from GEOS to QgsGeometry. > > This seems like a very reasonable interim solution until such time that a > type of 'collection' can be supported (no small feat, I am guessing). > > > Regards, > > Larry > > >> >> >> If this capability is not available in qgis is a problem of qgis not of >> geos. >> >> :) >> >> A. >> >> >> 2014-07-05 17:23 GMT+02:00 G. Allegri <[email protected]>: >> > (I changed the topic) >> > >> > Geometry collections in QGIS must be treated at the GEOS level. >> > There isnt a QGIS::wkbType for geometry collections, so if GEOS return a >> > collection they must be managed as GEOS geometries, before "moving them >> > up" >> > to QgsGeometry. >> > >> > Correct me if I'm wrong. >> > >> > giovanni >> > >> > >> > 2014-07-05 17:17 GMT+02:00 Andrea Peri <[email protected]>: >> >> >> >> Thx GioHappy, this is imprtant for me to know. >> >> >> >> So is surely better to use the postgis or spatialite >> >> because it allow you to extract from the collection the section with >> >> the right type. >> >> >> >> If you do a difference beetwen two polygons is the result is a >> >> collection with a polygon section and a point section. >> >> You should extract the polygon and discard the point. >> >> If the strategu is discard all the collection this mean that on qgis >> >> the difference could lost domething of important and so potentially >> >> the difference do a wrong result. >> >> >> >> Regards, >> >> Andrea. >> >> >> >> >> >> 2014-07-05 16:47 GMT+02:00 G. Allegri <[email protected]>: >> >> > AFAICS whenever a new feature needs to be created, geom collections >> >> > are >> >> > discarded, because QGIS cannot manage them. >> >> > >> >> > giovanni >> >> > >> >> > >> >> > 2014-07-05 16:40 GMT+02:00 Andrea Peri <[email protected]>: >> >> > >> >> >> Ok, sorry. >> >> >> >> >> >> Just a my personal curiosity: >> >> >> The difference could give also a collection not empty. >> >> >> If the difference of two polygons is a collection with some >> >> >> polygons, >> >> >> some lines and some points. >> >> >> What happened to this collection in QGIS ? >> >> >> >> >> >> Thx, >> >> >> A. >> >> >> >> >> >> >> >> >> 2014-07-05 16:03 GMT+02:00 G. Allegri <[email protected]>: >> >> >> > Hi Andrea, as I said above I'm not considering it an error. >> >> >> > The topic of this post is QGIS message logging. >> >> >> > The processing completes as expected, with the same results as >> >> >> > Spatialite >> >> >> > and PostGIS. These simply do it silently :) >> >> >> > >> >> >> > giovanni >> >> >> > >> >> >> > >> >> >> > >> >> >> > 2014-07-05 15:59 GMT+02:00 Andrea Peri <[email protected]>: >> >> >> > >> >> >> >> Hi GioHappy, >> >> >> >> >> >> >> >> the empty-collection is absolutelly not necessarylly a bug. >> >> >> >> It is the obviously result of an operation on a machine (like the >> >> >> >> computer) with a binary finite arithmetic. >> >> >> >> >> >> >> >> Usually the empty is due to a too low value to be describe with a >> >> >> >> finite binary arithmetic. >> >> >> >> >> >> >> >> If the dataset is small or it is topologically correct (this not >> >> >> >> mean >> >> >> >> only to be snapped). >> >> >> >> the collection results never happened. >> >> >> >> Instead if the dataset is not topologically correct and is big >> >> >> >> the >> >> >> >> probability to have some collection result grow. >> >> >> >> We tipically have alway an 0.01% of collection on our results. >> >> >> >> >> >> >> >> I suggest you to use directly postgis or spatialite to do this >> >> >> >> kind >> >> >> >> of >> >> >> >> operations. >> >> >> >> >> >> >> >> In these products you have the useful tools to resolve the >> >> >> >> collections >> >> >> >> correctly. >> >> >> >> >> >> >> >> Regard, >> >> >> >> >> >> >> >> Andrea. >> >> >> >> >> >> >> >> >> >> >> >> 2014-07-05 12:40 GMT+02:00 G. Allegri <[email protected]>: >> >> >> >> > Hi Jurgen, >> >> >> >> > I wouldn't call them errors. GEOSDIfference returned a lot of >> >> >> >> > empty >> >> >> >> > geomcollections, which the QgsVectorFileWriter couldn't manage. >> >> >> >> > Consequently >> >> >> >> > it wrote a log message for each geometry it couldn't write [1]. >> >> >> >> > >> >> >> >> > Surely the logging should be improved in this specific case. >> >> >> >> > Anyway, >> >> >> >> > I >> >> >> >> > think >> >> >> >> > the option to turn QgsMessageLog off could be useful anyway... >> >> >> >> > >> >> >> >> > giovanni >> >> >> >> > >> >> >> >> > [1] >> >> >> >> > >> >> >> >> > >> >> >> >> > >> >> >> >> > >> >> >> >> > https://github.com/qgis/QGIS/blob/master/src/core/qgsvectorfilewriter.cpp#L1718 >> >> >> >> > >> >> >> >> > >> >> >> >> > 2014-07-05 12:31 GMT+02:00 Jürgen E. <[email protected]>: >> >> >> >> > >> >> >> >> >> Hi Giovanni, >> >> >> >> >> >> >> >> >> >> On Sat, 05. Jul 2014 at 10:27:24 +0200, G. Allegri wrote: >> >> >> >> >> > As I reported in a previous post, I was unable to conclude a >> >> >> >> >> > difference >> >> >> >> >> > operation on a vector because the tool was running in >> >> >> >> >> > exponential >> >> >> >> >> > time. >> >> >> >> >> >> >> >> >> >> > Debugging pointed me to the problem: QgsVectoFileWriter was >> >> >> >> >> > logging >> >> >> >> >> > tons >> >> >> >> >> > of >> >> >> >> >> > empty geometres with an incompatible type which will be >> >> >> >> >> > discarded. >> >> >> >> >> > After commenting the line of logging the process completed >> >> >> >> >> > in >> >> >> >> >> > linear >> >> >> >> >> > time. >> >> >> >> >> >> >> >> >> >> > Shouldn't we offer the opportunity to turn QgsLogger off? >> >> >> >> >> > This >> >> >> >> >> > would >> >> >> >> >> > let >> >> >> >> >> > the user/developer to switch it off whenever he already >> >> >> >> >> > knows >> >> >> >> >> > what's >> >> >> >> >> > happening. >> >> >> >> >> > Is it already there and I missed it? >> >> >> >> >> >> >> >> >> >> What error message did you get and wouldn't it be better to >> >> >> >> >> kill >> >> >> >> >> them >> >> >> >> >> where it >> >> >> >> >> origins or to issue a final "%n empty geometries skipped" >> >> >> >> >> instead >> >> >> >> >> of >> >> >> >> >> logging >> >> >> >> >> individual errors. >> >> >> >> >> >> >> >> >> >> Alternatively we could issue a "last message repeated %n >> >> >> >> >> times" >> >> >> >> >> in >> >> >> >> >> message >> >> >> >> >> log >> >> >> >> >> to make it behave better - although that only works the error >> >> >> >> >> message >> >> >> >> >> are >> >> >> >> >> identical. >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> Jürgen >> >> >> >> >> >> >> >> >> >> -- >> >> >> >> >> Jürgen E. Fischer norBIT GmbH Tel. >> >> >> >> >> +49-4931-918175-31 >> >> >> >> >> Dipl.-Inf. (FH) Rheinstraße 13 Fax. >> >> >> >> >> +49-4931-918175-50 >> >> >> >> >> Software Engineer D-26506 Norden >> >> >> >> >> http://www.norbit.de >> >> >> >> >> QGIS release manager (PSC) Germany IRC: >> >> >> >> >> jef >> >> >> >> >> on >> >> >> >> >> FreeNode >> >> >> >> >> >> >> >> >> >> -- >> >> >> >> >> norBIT Gesellschaft fuer Unternehmensberatung und >> >> >> >> >> Informationssysteme >> >> >> >> >> mbH >> >> >> >> >> Rheinstrasse 13, 26506 Norden >> >> >> >> >> GF: Jelto Buurman, HR: Amtsgericht Emden, HRB 5502 >> >> >> >> >> >> >> >> >> >> _______________________________________________ >> >> >> >> >> Qgis-developer mailing list >> >> >> >> >> [email protected] >> >> >> >> >> http://lists.osgeo.org/mailman/listinfo/qgis-developer >> >> >> >> > >> >> >> >> > >> >> >> >> > >> >> >> >> > >> >> >> >> > -- >> >> >> >> > Giovanni Allegri >> >> >> >> > http://about.me/giovanniallegri >> >> >> >> > Twitter: https://twitter.com/_giohappy_ >> >> >> >> > blog: http://blog.spaziogis.it >> >> >> >> > GEO+ geomatica in Italia http://bit.ly/GEOplus >> >> >> >> > >> >> >> >> > _______________________________________________ >> >> >> >> > Qgis-developer mailing list >> >> >> >> > [email protected] >> >> >> >> > http://lists.osgeo.org/mailman/listinfo/qgis-developer >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> -- >> >> >> >> ----------------- >> >> >> >> Andrea Peri >> >> >> >> . . . . . . . . . >> >> >> >> qwerty àèìòù >> >> >> >> ----------------- >> >> >> > >> >> >> > >> >> >> > >> >> >> > >> >> >> > -- >> >> >> > Giovanni Allegri >> >> >> > http://about.me/giovanniallegri >> >> >> > Twitter: https://twitter.com/_giohappy_ >> >> >> > blog: http://blog.spaziogis.it >> >> >> > GEO+ geomatica in Italia http://bit.ly/GEOplus >> >> >> >> >> >> >> >> >> >> >> >> -- >> >> >> ----------------- >> >> >> Andrea Peri >> >> >> . . . . . . . . . >> >> >> qwerty àèìòù >> >> >> ----------------- >> >> > >> >> > >> >> > >> >> > >> >> > -- >> >> > Giovanni Allegri >> >> > http://about.me/giovanniallegri >> >> > Twitter: https://twitter.com/_giohappy_ >> >> > blog: http://blog.spaziogis.it >> >> > GEO+ geomatica in Italia http://bit.ly/GEOplus >> >> >> >> >> >> >> >> -- >> >> ----------------- >> >> Andrea Peri >> >> . . . . . . . . . >> >> qwerty àèìòù >> >> ----------------- >> > >> > >> > >> > >> > -- >> > Giovanni Allegri >> > http://about.me/giovanniallegri >> > Twitter: https://twitter.com/_giohappy_ >> > blog: http://blog.spaziogis.it >> > GEO+ geomatica in Italia http://bit.ly/GEOplus >> >> >> >> -- >> ----------------- >> Andrea Peri >> . . . . . . . . . >> qwerty àèìòù >> ----------------- >> _______________________________________________ >> Qgis-developer mailing list >> [email protected] >> http://lists.osgeo.org/mailman/listinfo/qgis-developer > > -- ----------------- Andrea Peri . . . . . . . . . qwerty àèìòù ----------------- _______________________________________________ Qgis-developer mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/qgis-developer
