Populating attribute table with attributes from table using PyQGIS

Question

I am trying to populate an attribute table of a feature with attributes from another feature. I have been able to segregate the input data into fields named "From", "Eastings" and "Northings". I find this is not such a difficult task to carry out as this code helped. The problem now is the input data has only four(4) rows but when I run my script, it multiplies the number of rows and I end up with twenty rows. I am quite sure I need to change something in the code, i am not sure where as I am relatively new to python.

here is my code:

pr.addAttributes([QgsField('FROM', QVariant.String)])
vpr.addAttributes([QgsField('Eastings', QVariant.Double)])
vpr.addAttributes([QgsField('Northings',QVariant.Double)])
vlayer.updateFields()
vlayer.startEditing()
for things in vlayer.getFeatures():
 for i in new_attribs:
 things['FROM'] = i[0] 
 things['Eastings'] = i[1]
 things['Northings']=i[2]
 things.setAttributes(i[0])
 vpr.addFeatures([things])
 
 vlayer.updateFeature(things)
 vlayer.commitChanges()

This is the result I get:

enter image description here

How do I get only the four(4) rows I need?

• Bera: What is new_attribs
• GeomaSmart: new_attribs is the attributes i need to populate the layer with.
• JULESG: vlayer already as 4 features at the begining but no attributes ? Is new_attribs a list of lists ? Like this : new_attribs = [["SGC A562 16 1", 1099307.4, 307285.64], ["SGC A562 16 2", 1099349.96, 307243.6], ["SGC A562 16 3", 1099249.74, 307139.4], ["SGC A562 16 4", 1099203.19, 307170.55]] if vlayer already as features I don't understand why you add more with vpr.addFeatures([things])

Answer 1

You need at least to change the code to the following. The main change has been desindenting vpr.addFeatures([things]) to avoid adding unwanted "garbage" features. I'm also surprised why you edit the vlayer if you want to add your feature to vpr?

pr.addAttributes([QgsField('FROM', QVariant.String)])
vpr.addAttributes([QgsField('Eastings', QVariant.Double)])
vpr.addAttributes([QgsField('Northings',QVariant.Double)])
vlayer.updateFields()
vlayer.startEditing()
for things in vlayer.getFeatures():
 for i in new_attribs:
 things['FROM'] = i[0] 
 things['Eastings'] = i[1]
 things['Northings'] = i[2]
 things.setAttributes(i[0])
 vpr.addFeatures([things])
 vlayer.updateFeature(things)
 vlayer.commitChanges()