SQL操作：Filter (FilterStreamOp)

Java 类名：com.alibaba.alink.operator.stream.sql.FilterStreamOp

Python 类名：FilterStreamOp

功能介绍

对流式数据进行sql的FILTER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]
])

stream_data = StreamOperator.fromDataframe(df, schemaStr='f1 string, f2 bigint, f3 double')

op = FilterStreamOp().setClause("f1='Ohio'")
stream_data = stream_data.link(op)

stream_data.print()
StreamOperator.execute()

Java 代码

import org.apache.flink.types.Row;

import com.alibaba.alink.operator.stream.StreamOperator;
import com.alibaba.alink.operator.stream.source.MemSourceStreamOp;
import com.alibaba.alink.operator.stream.sql.FilterStreamOp;
import org.junit.Test;

import java.util.Arrays;
import java.util.List;

public class FilterStreamOpTest {
	@Test
	public void testFilterStreamOp() 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)
		);
		StreamOperator <?> stream_data = new MemSourceStreamOp(df, "f1 string, f2 int, f3 double");
		StreamOperator <?> op = new FilterStreamOp().setClause("f1='Ohio'");
		stream_data = stream_data.link(op);
		stream_data.print();
		StreamOperator.execute();
	}
}

运行结果

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