Working with Pandas

How can we benefit from a MultiIndex? If we take a loot at the data set, we can see that we have for each country the same set of dates. In this case it would make sense to structure the index hierarchically, by having different dates for each country. This is where the MultiIndex comes to play. Now, in order to set a MultiIndex we need to choose these two columns by by setting the index with set_index.

df.set_index(['country', 'date'], inplace=True)

df.head()