To use GroupBy with a Python Pandas DataFrame and select most common value, we can use the pd.Series.mode aggregation.
For instance, we write
source.groupby(['Country','City'])['Short name'].agg(pd.Series.mode)
to call groupby on the source data frame.
And then we get the mode of the 'Short name' column values by calling agg with pd.Series.Mode.
We can convert thge returned result into a dataframe with the to_frame method.
For instance, we can write
source.groupby(['Country','City'])['Short name'].agg(pd.Series.mode).to_frame()
to call to_frame on the result to convert it to a data frame.
