SQL操作：Where (WhereBatchOp)

Java 类名：com.alibaba.alink.operator.batch.sql.WhereBatchOp

Python 类名：WhereBatchOp

功能介绍

对批式数据进行sql的WHERE操作。

参数说明

名称	中文名称	描述	类型	是否必须？	取值范围	默认值
clause	运算语句	运算语句	String	✓

代码示例

Python 代码

from pyalink.alink import *

import pandas as pd

useLocalEnv(1)

df = pd.DataFrame([
    ['Ohio', 2000, 1.5],
    ['Ohio', 2001, 1.7],
    ['Ohio', 2002, 3.6],
    ['Nevada', 2001, 2.4],
    ['Nevada', 2002, 2.9],
    ['Nevada', 2003, 3.2]
])
batch_data = BatchOperator.fromDataframe(df, schemaStr='f1 string, f2 bigint, f3 double')
batch_data.link(WhereBatchOp().setClause("f1='Ohio'"))

Java 代码

import com.alibaba.alink.operator.batch.BatchOperator;
import com.alibaba.alink.operator.batch.source.MemSourceBatchOp;
import com.alibaba.alink.operator.batch.sql.WhereBatchOp;
import org.junit.Test;

public class WhereBatchOpTest {
	@Test
	public void testWhereBatchOp() throws Exception {
		List <Row> df = Arrays.asList(
            Row.of("Ohio", 2000, 1.5),
        	Row.of("Ohio", 2001, 1.7),
        	Row.of("Ohio", 2002, 3.6),
        	Row.of("Nevada", 2001, 2.4),
        	Row.of("Nevada", 2002, 2.9),
        	Row.of("Nevada", 2003, 3.2)
        );
	    BatchOperator <?> data = new MemSourceBatchOp(df, "f1 string, f2 int, f3 double");
        data.link(new WhereBatchOp().setClause("f1='Ohio'")).print();
	}
}

运行结果

f1	f2	f3
Ohio	2000	1.5000
Ohio	2001	1.7000
Ohio	2002	3.6000