输入：

New York,1,1000.00
New York,2,2000.00
New York,1,2000.00
Chicago,1,4000.00
Chicago,1,1500.00

方法1：
Pig脚本：

rental_data = LOAD 'rental_data.csv'  USING  PigStorage(',') AS (city:chararray, num_bedrooms: long, price:double);
rental_data_grp_city = GROUP rental_data BY (city);
rental_kpi = FOREACH rental_data_grp_city {
    one_bed_room = FILTER rental_data BY num_bedrooms==1;
    two_bed_room = FILTER rental_data BY num_bedrooms==2;
    GENERATE group AS city, AVG(one_bed_room.price) AS one_bed_price, AVG(two_bed_room.price) AS tow_bed_price;
};

输出：dump-u kpi:

(Chicago,2750.0,)
 (New York,1500.0,2000.0)

方法2：
Pig脚本：

rental_data = LOAD 'rental_data.csv'  USING  PigStorage(',') AS (city:chararray, num_bedrooms: long, price:double);
rental_data_grp_city = GROUP rental_data BY (city,num_bedrooms);
rental_kpi = FOREACH rental_data_grp_city {
    prices_bag = rental_data.price;
    GENERATE group.city AS city, group.num_bedrooms AS num_bedrooms, AVG(prices_bag) AS price; 
}

输出：dump-u kpi:

(Chicago,1,2750.0)
(New York,2,2000.0)
(New York,1,1500.0)