Re: [Qgis-developer] Select By Attribute

[Michael McInnis]

Thank you so much. I really appreciate your help!

Michael McInnis
6033 44th Ave. N.E.
Seattle, WA 98115
206 517-4701

Date: Fri, 28 Feb 2014 07:21:21 +0100
From: denis.rouz...@gmail.com
To: mmcinni...@msn.com; qgis-developer@lists.osgeo.org
Subject: Re: [Qgis-developer] Select By Attribute


  

  
  


On 27. 02. 14 18:41, Michael McInnis
  wrote:



  
  Desperately need help doing attribute based
selection :


  

  
  How do I select all features in a LAYER that the Field
LWFLAG != 'P'
  

  
  Python Console
  




from osgeo import ogr
canvas = qgis.utils.iface.mapCanvas()
allLayers = canvas.layers()
for i in allLayers: i.selectAll();
  print i.name(); print
  i.selectedFeatureCount()
 
for i in allLayers: i.selectAll();
  print i.name(); print
  i.selectedFeatureCount()
i.getFeatures(QgsFeatureRequest().setFilterExpression(‘
“LWFLAGS”
  != \’P\’) )
  

  

this is a feature iterator [0], so you need iterate



f = QgsFeature()

toSelect = []

while i.getFeatures(QgsFeatureRequest().setFilterExpression(‘
“LWFLAGS” != \’P\’) ).nextFeature(f):

toSelect.append(f.id())

i.setSelectedFeatures(toSelect)



[0] http://qgis.org/api/classQgsFeatureIterator.html




  

  

 

exp =
QgsExpression(‘LWFLAG <> “P” ’) 

  

  


  

  
  

  
  

  ___
Qgis-developer mailing list
Qgis-developer@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/qgis-developer


  ___
Qgis-developer mailing list
Qgis-developer@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/qgis-developer

Re: [Qgis-developer] Select By Attribute

[Michael McInnis]

Oh, Man, Thanks ! 
I can't wait to work with this today !

Michael McInnis
6033 44th Ave. N.E.
Seattle, WA 98115
206 517-4701

From: madman...@gmail.com
Date: Fri, 28 Feb 2014 16:26:06 +1000
Subject: Re: [Qgis-developer] Select By Attribute
To: denis.rouz...@gmail.com
CC: mmcinni...@msn.com; qgis-developer@lists.osgeo.org

We can make that even easier:
toSelect = []
for feature in layer.getFeatures(QgsFeatureRequest(‘“LWFLAGS” != \’P\’')):

 toSelect.append(feature.id())layer.setSelectedFeatures(toSelect)


  ___
Qgis-developer mailing list
Qgis-developer@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/qgis-developer

[Qgis-developer] Select By Attribute

[Michael McInnis]

Desperately need help doing attribute based selection :

How do I select all features in a LAYER that the Field LWFLAG != 'P'
Python Console

from osgeo import ogr

canvas = qgis.utils.iface.mapCanvas()

allLayers = canvas.layers()

for i in allLayers: i.selectAll(); print i.name(); print
i.selectedFeatureCount()

 

for i in allLayers: i.selectAll(); print i.name(); print
i.selectedFeatureCount()

i.getFeatures(QgsFeatureRequest().setFilterExpression(‘
“LWFLAGS” != \’P\’) )

 

exp =
QgsExpression(‘LWFLAG <> “P” ’) 


  ___
Qgis-developer mailing list
Qgis-developer@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/qgis-developer

[Qgis-developer] Still can't select features prior to dissolve

[Michael McInnis]

// This works 

from osgeo import ogr

canvas =
qgis.utils.iface.mapCanvas()

allLayers = canvas.layers()

for i in allLayers: i.selectAll(); print i.name(); print
i.selectedFeatureCount()
(In the python Console)
Above you use the current layer (i) to i.selectAll();
How do you do a selection using attribute values such as 
i.selectFeatures("LWFLAG" != 'P')
to set the selected features for the dissolve function?
qgis.analysis.QgsGeometryAnalyzer.dissolve?4(QgsVectorLayer,
QString, bool onlySelectedFeatures=True, int uniqueIdField=-1) -> bool
Michael McInnis
6033 44th Ave. N.E.
Seattle, WA 98115
206 517-4701  ___
Qgis-developer mailing list
Qgis-developer@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/qgis-developer

[Qgis-developer] Run Dissolve with selected features

[Michael McInnis]

Greetings Devs,
I have a large number of shapefiles I need to process and have had limited 
success using QGis 2.0.1 with it's python console.
// This works - 
from osgeo import ogr

canvas =
qgis.utils.iface.mapCanvas()

allLayers = canvas.layers()

for i in allLayers: i.selectAll(); print i.name(); print
i.selectedFeatureCount()
// What I can't figure out is how to throw in a selection and then run Dissove 
on it.
I've tried 
for i in allLayers: i.selectAll(); print i.name(); 
i.getFeatures(QgsFeatureRequest().QgsExpression('LWFLAG <> "P" '); print 
i.selectedFeatureCount()andselExp = QgsExpression('LWFLAG <> "P" ')for i in 
allLayers: i.selectAll(); print i.name(); 
i.getFeatures(QgsFeatureRequest(selExp); print i.selectedFeatureCount()
andfor i in allLayers: i.selectAll(); print i.name(); 
i.getFeatures(QgsFeatureRequest('LWFLAG <> "P" ')); print 
i.selectedFeatureCount()
and several other techniques all to no avail. 
In PseudoCode:
from osgeo import ogrcanvas = qgis.utils.iface.mapCanvas()allLayers = 
canvas.layers()for i in allLayers:   i.select('LWFLAG <> "P" ');   
print i.name();   print i.selectedFeatureCount();  i.dissolve("use 
sel", i.name() + '_dis', "BLOCKGRP");
  ___
Qgis-developer mailing list
Qgis-developer@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/qgis-developer