Field Value shapefile - Add values

Question

I have a shapefile that contains three lines. I want to add a specific numeric id to the field "line_id" and a string id to the field "border_id". Basically, for the first line, I want to add the value '1' to "line_id" and 'North' to field "border_id". For the second line I want to add the value '2' to "line_id" and 'South' to field "border_id".

Here is my code, I think I don't get how the changeAttributeValues command works on pyQGIS.

lyr.startEditing()
provider = lyr.dataProvider()
provider.addAttributes([QgsField("line_id",QVariant.Double),(QgsField("border_id",QVariant.String))])
lyr.updateFields()
lyr.commitChanges()

Answer 1

I propose to use the following code in case you have two features in the lyrr.

values = {1: 'North', 2: 'South'}
counter = 0
for feat in lyr.getFeatures():
    counter += 1
    feat.setAttribute('line_id', counter)
    feat.setAttribute('border_id', values[counter])
    lyr.updateFeature(feat)
lyr.commitChanges()

It will work for python 3.6 and qgis 3.2