When I go to layer --> properties --> Legend, I can add text on symbols from an expression like round($length , 5).
After reading the document here https://qgis.org/pyqgis/3.0/core/Legend/QgsLegendSymbolItem.html#qgis.core.QgsLegendSymbolItem.setSymbol, I tried to code it as below.
symbols = QgsSymbol.defaultSymbol(line_layer.geometryType()) QgsLegendSymbolItem(symbols, "$length").setSymbol(symbols)
and it gives me error like
TypeError: QgsLegendSymbolItem(): arguments did not match any overloaded call: overload 1: too many arguments overload 2: not enough arguments overload 3: argument 1 has unexpected type 'QgsLineSymbol'
I want to do this using PyQGIS but I am having no luck, My layer is categorized into features by feature id.
I am an intern and fairly new to PyQGIS.