Selecting and updating attribute values using Python console in QGIS?
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I am working with Landusefc and Class columns (ref table).
What I want is: Selecting all water from "Class" and giving a value say '8' in the "Landusefc" column for these selected features.
Table looks like
I have tried the following code, it works till the selection part but doesn't seem to change the attribute value using the ChangeAttributeValue.
from qgis.core import *
import processing
layer=processing.getObject('test1')
query= ' "class" = 'Water' '
selection = layer.getFeatures(QgsFeatureRequest().setFilterExpression(query))
layer.setSelectedFeatures([k.id() for k in selection])
#using change Attribute to change the value of the selected feature
layer.startEditing()
for feat in selection:
layer.changeAttributeValue(feat.id(), 5, 8)
layer.commitChanges()
qgis pyqgis select-by-attribute
edited Apr 11 at 7:48
Kadir Şahbaz
4,69221531
asked Apr 11 at 6:45
ShellyShelly
262
add a comment |
I am working with Landusefc and Class columns (ref table).
What I want is: Selecting all water from "Class" and giving a value say '8' in the "Landusefc" column for these selected features.
Table looks like
I have tried the following code, it works till the selection part but doesn't seem to change the attribute value using the ChangeAttributeValue.
from qgis.core import *
import processing
layer=processing.getObject('test1')
query= ' "class" = 'Water' '
selection = layer.getFeatures(QgsFeatureRequest().setFilterExpression(query))
layer.setSelectedFeatures([k.id() for k in selection])
#using change Attribute to change the value of the selected feature
layer.startEditing()
for feat in selection:
layer.changeAttributeValue(feat.id(), 5, 8)
layer.commitChanges()
qgis pyqgis select-by-attribute
edited Apr 11 at 7:48
Kadir Şahbaz
4,69221531
asked Apr 11 at 6:45
ShellyShelly
262
add a comment |
I am working with Landusefc and Class columns (ref table).
What I want is: Selecting all water from "Class" and giving a value say '8' in the "Landusefc" column for these selected features.
Table looks like
I have tried the following code, it works till the selection part but doesn't seem to change the attribute value using the ChangeAttributeValue.
from qgis.core import *
import processing
layer=processing.getObject('test1')
query= ' "class" = 'Water' '
selection = layer.getFeatures(QgsFeatureRequest().setFilterExpression(query))
layer.setSelectedFeatures([k.id() for k in selection])
#using change Attribute to change the value of the selected feature
layer.startEditing()
for feat in selection:
layer.changeAttributeValue(feat.id(), 5, 8)
layer.commitChanges()
qgis pyqgis select-by-attribute
edited Apr 11 at 7:48
Kadir Şahbaz
4,69221531
asked Apr 11 at 6:45
ShellyShelly
262
I am working with Landusefc and Class columns (ref table).
What I want is: Selecting all water from "Class" and giving a value say '8' in the "Landusefc" column for these selected features.
Table looks like
I have tried the following code, it works till the selection part but doesn't seem to change the attribute value using the ChangeAttributeValue.
from qgis.core import *
import processing
layer=processing.getObject('test1')
query= ' "class" = 'Water' '
selection = layer.getFeatures(QgsFeatureRequest().setFilterExpression(query))
layer.setSelectedFeatures([k.id() for k in selection])
#using change Attribute to change the value of the selected feature
layer.startEditing()
for feat in selection:
layer.changeAttributeValue(feat.id(), 5, 8)
layer.commitChanges()
qgis pyqgis select-by-attribute
qgis pyqgis select-by-attribute
edited Apr 11 at 7:48
Kadir Şahbaz
4,69221531
asked Apr 11 at 6:45
ShellyShelly
262
edited Apr 11 at 7:48
Kadir Şahbaz
4,69221531
asked Apr 11 at 6:45
ShellyShelly
262
edited Apr 11 at 7:48
Kadir Şahbaz
4,69221531
edited Apr 11 at 7:48
Kadir Şahbaz
4,69221531
edited Apr 11 at 7:48
Kadir Şahbaz
4,69221531
4,69221531
asked Apr 11 at 6:45
ShellyShelly
262
asked Apr 11 at 6:45
ShellyShelly
262
asked Apr 11 at 6:45
ShellyShelly
262
262
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
SOLUTION 1:
You have to remove layer.setSelectedFeatures([k.id() for k in selection]).
Because selection = layer.getFeatures(QgsFeatureRequest().setFilterExpression(query)) line gives you a QgsFeatureIterator, that's an iterator. When you use that iterator once, you reach the end of the iterator. Then, if you use it again, you get nothing.
In your case, when you use selection variable (it's an iterator now) in [k.id() for k in selection], you reach the end. If you use selection in for loop, since you are at the end of the iterator, you don't have any feature now. If you want to be certain, you can add a print("Foo") line to for loop.
SOLUTION 2:
Change for feat in selection: into for feat in layer.selectedFeatures():. This solution works only on QGIS 2.x.
answered Apr 11 at 7:46
Kadir ŞahbazKadir Şahbaz
4,69221531
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
SOLUTION 1:
You have to remove layer.setSelectedFeatures([k.id() for k in selection]).
Because selection = layer.getFeatures(QgsFeatureRequest().setFilterExpression(query)) line gives you a QgsFeatureIterator, that's an iterator. When you use that iterator once, you reach the end of the iterator. Then, if you use it again, you get nothing.
In your case, when you use selection variable (it's an iterator now) in [k.id() for k in selection], you reach the end. If you use selection in for loop, since you are at the end of the iterator, you don't have any feature now. If you want to be certain, you can add a print("Foo") line to for loop.
SOLUTION 2:
Change for feat in selection: into for feat in layer.selectedFeatures():. This solution works only on QGIS 2.x.
answered Apr 11 at 7:46
Kadir ŞahbazKadir Şahbaz
4,69221531
add a comment |
SOLUTION 1:
You have to remove layer.setSelectedFeatures([k.id() for k in selection]).
Because selection = layer.getFeatures(QgsFeatureRequest().setFilterExpression(query)) line gives you a QgsFeatureIterator, that's an iterator. When you use that iterator once, you reach the end of the iterator. Then, if you use it again, you get nothing.
In your case, when you use selection variable (it's an iterator now) in [k.id() for k in selection], you reach the end. If you use selection in for loop, since you are at the end of the iterator, you don't have any feature now. If you want to be certain, you can add a print("Foo") line to for loop.
SOLUTION 2:
Change for feat in selection: into for feat in layer.selectedFeatures():. This solution works only on QGIS 2.x.
answered Apr 11 at 7:46
Kadir ŞahbazKadir Şahbaz
4,69221531
add a comment |
SOLUTION 1:
You have to remove layer.setSelectedFeatures([k.id() for k in selection]).
Because selection = layer.getFeatures(QgsFeatureRequest().setFilterExpression(query)) line gives you a QgsFeatureIterator, that's an iterator. When you use that iterator once, you reach the end of the iterator. Then, if you use it again, you get nothing.
In your case, when you use selection variable (it's an iterator now) in [k.id() for k in selection], you reach the end. If you use selection in for loop, since you are at the end of the iterator, you don't have any feature now. If you want to be certain, you can add a print("Foo") line to for loop.
SOLUTION 2:
Change for feat in selection: into for feat in layer.selectedFeatures():. This solution works only on QGIS 2.x.
answered Apr 11 at 7:46
Kadir ŞahbazKadir Şahbaz
4,69221531
SOLUTION 1:
You have to remove layer.setSelectedFeatures([k.id() for k in selection]).
Because selection = layer.getFeatures(QgsFeatureRequest().setFilterExpression(query)) line gives you a QgsFeatureIterator, that's an iterator. When you use that iterator once, you reach the end of the iterator. Then, if you use it again, you get nothing.
In your case, when you use selection variable (it's an iterator now) in [k.id() for k in selection], you reach the end. If you use selection in for loop, since you are at the end of the iterator, you don't have any feature now. If you want to be certain, you can add a print("Foo") line to for loop.
SOLUTION 2:
Change for feat in selection: into for feat in layer.selectedFeatures():. This solution works only on QGIS 2.x.
answered Apr 11 at 7:46
Kadir ŞahbazKadir Şahbaz
4,69221531
edited Apr 11 at 9:08
answered Apr 11 at 7:46
Kadir ŞahbazKadir Şahbaz
4,69221531
answered Apr 11 at 7:46
Kadir ŞahbazKadir Şahbaz
4,69221531
answered Apr 11 at 7:46
Kadir ŞahbazKadir Şahbaz
4,69221531
4,69221531
add a comment |
add a comment |
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