Send the following on WhatsApp
Continue to ChatQGIS - Creating new column from existing using Python https://arunmozhi.in/2019/01/08/qgis-creating-new-column-from-existing-using-python/
QGIS - Creating new column from existing using Python https://arunmozhi.in/2019/01/08/qgis-creating-new-column-from-existing-using-python/