We can see that an index (0,1,2, ...) has been automatically assigned to the DataFrame. We can also assign a custom index to the DataFrame object:
ordinals = ["first", "second",
"third", "fourth",
"fifth", "sixth",
"seventh", "eigth",
"ninth", "tenth",
"eleventh", "twelvth",
"thirteenth"]
city_frame = pd.DataFrame(cities,
columns=["name",
"country", "population"],
index=ordinals)
print(city_frame)