PREDICT BY
功能描述
利用完成训练的模型进行推测任务。
注意事项
调用的模型名称在系统表GS_MODEL_WAREHOUSE中可查看到。
语法格式
PREDICT BY model_name [ (FEATURES attribute [, attribute] +]) ]
参数说明
model_name
用于推测任务的模型名称。
取值范围：字符串，需要符合标识符的命名规则。
attribute
推测任务的输入特征列名。
取值范围：字符串，需要符合标识符的命名规则。
示例
示例1：
创建模型的步骤参见CREATE MODEL的示例。
SELECT id, PREDICT BY price_model (FEATURES size), price FROM houses;
返回结果如下：
id | price_model_pred | price
----+------------------+-------
1 | 4 | 4
5 | 8 | 8
(2 rows)
示例2：
1、创建数据表。
CREATE TABLE houses (
id INTEGER,
tax INTEGER,
bedroom INTEGER,
bath DOUBLE PRECISION,
price INTEGER,
size INTEGER,
lot INTEGER,
mark text
);
2、插入训练数据。
INSERT INTO houses(id, tax, bedroom, bath, price, size, lot, mark) VALUES
(1,590,2,1,50000,770,22100,'a+'),
(2,1050,3,2,85000,1410,12000,'a+'),
(3,20,2,1,22500,1060,3500,'a-'),
(4,870,2,2,90000,1300,17500,'a+'),
(5,1320,3,2,133000,1500,30000,'a+'),
(6,1350,2,1,90500,850,25700,'a-'),
(7,2790,3,2.5,260000,2130,25000,'a+'),
(8,680,2,1,142500,1170,22000,'a-'),
(9,1840,3,2,160000,1500,19000,'a+'),
(10,3680,4,2,240000,2790,20000,'a-'),
(11,1660,3,1,87000,1030,17500,'a+'),
(12,1620,3,2,118500,1250,20000,'a-'),
(13,3100,3,2,140000,1760,38000,'a+'),
(14,2090,2,3,148000,1550,14000,'a-'),
(15,650,3,1.5,65000,1450,12000,'a-');
3、训练模型。
CREATE MODEL price_model USING logistic_regression
FEATURES size, lot
TARGET mark
FROM HOUSES
WITH learning_rate=0.88, max_iterations=default;
4、预测。
SELECT id, PREDICT BY price_model (FEATURES size,lot) FROM houses;
5、模型进行模型解析文本化任务。
select gs_explain_model('price_model');
6、删除模型和表。
DROP MODEL price_model;
DROP TABLE houses;
