How to dissolve two geodataframes, using multiple columns to group by

Question

I want to dissolve a dataframe grouped by two columns. However, in the documentation of the Dissolve function only one column is provided:

GeoDataFrame.dissolve(by=None, aggfunc='first', as_index=True,
level=None, sort=True, observed=False, dropna=True)

The columns of the dataframe can be thought of like this:

State, Districts, City, Number_Inhabitantes

Instead of the syntax given in the documentation, I would like to do something similar to this, to get the number of Inhabitants per District instead of having the Number of Inhabitantes per city:

GeoDataFrame.dissolve(by= "State"&"Districts",aggfunc={"Number_Inhabitantes": "count"} )

Is there a way to do this?

Answer 1

Yes, it is pretty straightforward : the by argument can be a list of column names, even though the doc doesn't mention this. So to obtain "the number of Inhabitants per District", you may use the following :

gdf.dissolve(by=['States', 'Districts'], aggfunc={'Number_Inhabitantes': 'sum'})

N.B.: this will result in a multi-indexed dataframe.