pandas filter rows by value
# does year equals to 2002?
# is_2002 is a boolean variable with True or False in it
>is_2002 = gapminder['year']==2002
>print(is_2002.head())
0 False
1 False
2 False
3 False
4 False
# filter rows for year 2002 using the boolean variable
>gapminder_2002 = gapminder[is_2002]
>print(gapminder_2002.shape)
(142, 6)