Splitting attribute value and inserting data into columns in QGIS using Python

Question

I am trying to separate a string value from a field and then put it into its releated Field.

The field name are characters in the string and its value is the number.

"Field"=PT 100BC 20cd 19 is the string value

PT= 100, BC=20 cd=19.

the string is irregular.

the column names are the characters in the string and number is the value associated with it.

I have so far done this.

from qgis.core import *
import qgis.utils

inlayer=iface.activeLayer()

inlayer.selectByExpression('"TRTMTHD1"=\'PLANT\'or "TRTMTHD1"=\'NATURAL\' ')
selection=inlayer.selectedFeatures()

for s in selection:
    d=(sl.split() for sl in s)

If they do the split the result is PT, 100BC, 20CD which I do not want.

Which command do I use to split the value in field column and then update the record?

After I run this

{from qgis.core import * import qgis.utils

layer=iface.activeLayer() fc=layer.featureCount() f_list=[] for i in range(0,fc): feat=layer.getFeature(i) f_list.append(feat['SPCOMP'])

field_list=[] for f in layer.fields(): if len(f.name())==2: field_list.append(f.name())

layer.selectByExpression('"TRTMTHD1"=\'PLANT\'or "TRTMTHD1"=\'NATURAL\' ') selection=layer.selectedFeatures()

for string in f_list: if string!=None: for fn in field_list: string=string.replace(fn,',' + fn)

list_of_field_values=(string.split(',') for string in f_list)
for fvl in list_of_field_values:
    if fvl !='':
        fd,vl=fvl.split(' ')
        print('field=',fd,'value=',vd)}



I get AttributeError: 'list' object has no attribute 'split'

Answer 1

# splitting the string
list_of_fieldnames = ['PT', 'BC', 'cd', 'f1', 'f2', 'f3']

string1 = 'PT 100BC 20cd 19'
string2 = 'f3 3f1 1PT 100cd 19'

for string in [string1, string2]:
    for field in list_of_fieldnames:
        string = string.replace(field, ',' + field)

    list_of_fields_and_values = string.split(',')
    print(list_of_fields_and_values)
    for field_and_value in list_of_fields_and_values:
        if field_and_value != '':
            field, value = field_and_value.split(' ')
            print('field=', field, 'value=', value)

# update field value
# the layer is qgis.core.QgsVectorLayer
# https://qgis.org/pyqgis/3.6/core/QgsVectorLayer.html

layer.startEditing()
# check fid, field, newValue parameters at https://qgis.org/pyqgis/3.6/core/QgsVectorLayer.html#qgis.core.QgsVectorLayer.changeAttributeValue
layer.changeAttributeValue(fid, field, newValue)
layer.commitChanges()