Add a New Column

import pandas as pd
data = {
    'city' : ['Toronto', 'Montreal', 'Waterloo'],
    'points' : [80, 70, 90]
}
data
{'city': ['Toronto', 'Montreal', 'Waterloo'], 'points': [80, 70, 90]}

type(data)
dict

df = pd.DataFrame(data)
df
city points
0 Toronto 80
1 Montreal 70
2 Waterloo 90 
df = df.assign(code = [1, 2, 3])
df
city points code
0 Toronto 80 1
1 Montreal 70 2
2 Waterloo 90 3