[Qgis-developer] update plugin to QGIS 2.0

Fri Aug 2 07:58:38 PDT 2013

Hi,

thanks for the hint. And if I need the value of the raster? If I understand
correctly, ident will always be 1, if I have a 1 band raster layer. But how
can I get the value at QgsPoint(x,y) of the raster? I don't understand that
from the value tool plugin.

In QGIS 1.8 I use :

success, data = layer.identify(QgsPoint(x,y))
   for band, value in data.items():
   return value

and in QGIS 2.0:

ident = layer.dataProvider().identify(QgsPoint(x,y),QgsRaster.IdentifyFormatValue).results()
   ?

Thanks again

Otto

Am Fri, 2 Aug 2013 08:50:08 -0300
schrieb Etienne Tourigny <etourigny.dev at gmail.com>:

> from the api
> http://www.qgis.org/api/classQgsRasterIdentifyResult.html#a8537d25fdff215e7e9650b71a0a16783
> 
> results() returns a QMap<int, QVariant> (one item for each band), it
> does not return a tuple, so you should actually call
> 
> ident =
> layer.dataProvider().identify(QgsPoint(x,y),QgsRaster.IdentifyFormatValue).results()
> 
> and then test that ident is not empty (i,e. ident is not None and
> ident.iterkeys() is not None)
> 
> for each band, if the point is outside of the raster extent or is
> nodata, the value will be a null QVariant (i.e. QVariant()) which in
> python is None.
> 
> 
> cheers
> Etienne
> 
> On Fri, Aug 2, 2013 at 7:13 AM, Otto Dassau <dassau at gbd-consult.de> wrote:
> >
> > Hi,
> >
> > thanks for your hints, I think I am on the right track now. I had a look
> > at the value tool plugin and tried to adapt the method accordingly:
> >
> > def sampleRaster20(self, layer, x, y):
> >    #success, data = layer.dataProvider().identify(QgsPoint(x,y))
> >    success, data =
> > layer.dataProvider().identify(QgsPoint(x,y),QgsRaster.IdentifyFormatValue).results()
> > for band, value in data.items(): return value
> >
> > But now I get another error message
> >
> >  File
> >  "/home/dassau/.qgis2/python/plugins/weibullanalyse/weibullanalysedialog.py",
> >  line 448, in printValue self.showValues() File
> >  "/home/dassau/.qgis2/python/plugins/weibullanalyse/weibullanalysedialog.py",
> >  line 454, in showValues self.plot() File
> >  "/home/dassau/.qgis2/python/plugins/weibullanalyse/weibullanalysedialog.py",
> >  line 526, in plot w =
> > float(self.sampleRaster(self.InRastW.currentText(), self.xCoord,
> > self.yCoord))/10 File
> > "/home/dassau/.qgis2/python/plugins/weibullanalyse/weibullanalysedialog.py",
> > line 300, in sampleRaster return self.sampleRaster20(layer, x, y) File
> > "/home/dassau/.qgis2/python/plugins/weibullanalyse/weibullanalysedialog.py",
> > line 285, in sampleRaster20 success, data =
> > layer.dataProvider().identify(QgsPoint(x,y),
> > QgsRaster.IdentifyFormatValue ).results() ValueError: need more than 1
> > value to unpack
> >
> > Do you have an idea for this, too?
> >
> > Thanks
> > Otto
> >
> > Am Thu, 1 Aug 2013 16:00:08 -0300
> > schrieb Etienne Tourigny <etourigny.dev at gmail.com>:
> >
> > > Have a look at the source of the value tool plugin, it calls the
> > > identify() method and has been updated to 2.0 api.
> > >
> > > Etienne
> > >
> > > On Thu, Aug 1, 2013 at 1:58 PM, Otto Dassau <dassau at gbd-consult.de>
> > > wrote:
> > >
> > > > Hi,
> > > >
> > > > I want to update a plugin from 1.8 to QGIS 2.0 and it throws
> > > > following error:
> > > >
> > > > Traceback (most recent call last):
> > > > File
> > > >
> > > >
> > > > "/home/dassau/.qgis2/python/plugins/weibullanalyse/weibullanalysedialog.py",
> > > > line 447, in printValue self.showValues() File
> > > >
> > > >
> > > > "/home/dassau/.qgis2/python/plugins/weibullanalyse/weibullanalysedialog.py",
> > > > line 453, in showValues self.plot() File
> > > >
> > > >
> > > > "/home/dassau/.qgis2/python/plugins/weibullanalyse/weibullanalysedialog.py",
> > > > line 514, in plot w =
> > > > float(self.sampleRaster(self.InRastW.currentText(), self.xCoord,
> > > > self.yCoord))/10 File
> > > >
> > > >
> > > > "/home/dassau/.qgis2/python/plugins/weibullanalyse/weibullanalysedialog.py",
> > > > line 299, in sampleRaster return self.sampleRaster20(layer, x, y)
> > > > File
> > > >
> > > >
> > > > "/home/dassau/.qgis2/python/plugins/weibullanalyse/weibullanalysedialog.py",
> > > > line 284, in sampleRaster20 success, data =
> > > > layer.dataProvider().identify(QgsPoint(x,y))
> > > >
> > > > TypeError:
> > > > QgsRasterDataProvider.identify(QgsPoint, QgsRaster.IdentifyFormat,
> > > > QgsRectangle theExtent=QgsRectangle(), int theWidth=0, int
> > > > theHeight=0): not enough arguments
> > > >
> > > > I found at
> > > > http://hub.qgis.org/wiki/quantum-gis/API_changes_for_version_20 the
> > > > section QgsRasterDataProvider which should fit. And the Method,
> > > > where I assume the error occurs should be this
> > > >
> > > > # get value at mouse position QGIS <= 1.8 (working for 1.8)
> > > > def sampleRaster18(self, layer, x, y):
> > > >    success, data = layer.identify(QgsPoint(x,y))
> > > >    for band, value in data.items():
> > > >      return value
> > > >
> > > > now what I tried but doesn't work (see error above)
> > > >
> > > > # get value at mouse position QGIS >= 2.0 (not working yet :()
> > > > def sampleRaster20(self, layer, x, y):
> > > >    success, data = layer.dataProvider().identify(QgsPoint(x,y))
> > > >    for band, value in data.items():
> > > >      return value
> > > >
> > > > my problem is, that I don't understand how to implement in
> > > > sampleRaster20 the new method from the API_changes_for_version_20
> > > > website which says:
> > > >
> > > > QMap<int, QVariant> identify( const QgsPoint & thePoint,
> > > > IdentifyFormat theFormat, const QgsRectangle &theExtent =
> > > > QgsRectangle(), int theWidth = 0, int theHeight = 0 )
> > > >
> > > > can anybody help?
> > > >
> > > > Thanks
> > > >
> > > > Otto
> > > > _______________________________________________
> > > > Qgis-developer mailing list
> > > > Qgis-developer at lists.osgeo.org
> > > > http://lists.osgeo.org/mailman/listinfo/qgis-developer
> > > >
> >
> >
> > --
> > Geoinformatik Büro Dassau - http://www.gbd-consult.de
> > FOSSGIS consulting , training , support  and analysis
> > Ackerstrasse 144c  ,  D - 40233 Düsseldorf  , Germany
> > Tel: +49-(0)211-47468178 , Mobil: +49-(0)171-4687540
> >
> > --
> > Community Advisor - QGIS Project Steering Committee

-- 
Geoinformatik Büro Dassau - http://www.gbd-consult.de
FOSSGIS consulting , training , support  and analysis
Ackerstrasse 144c  ,  D - 40233 Düsseldorf  , Germany
Tel: +49-(0)211-47468178 , Mobil: +49-(0)171-4687540

--
Community Advisor - QGIS Project Steering Committee