Entities in dataframe

[soininen]

dataframes.to_dataframe() currently takes a parameter value item and turns it into a Pandas dataframe. The function could also work on entity class items turning them into dataframes with columns

entity_class_name - dimension 1 - ... - dimension N

For example:

entity_class_name	unit	node
unit__from_node	power_plant_a	fuel_node
unit__from_node	power_plant_b	fuel_node
unit__from_node	power_plant_a	electricity_node
unit__from_node	power_plant_b	electricity_node

Reported by @jkiviluo