Java 类名：com.alibaba.alink.operator.stream.sql.WhereStreamOp
Python 类名：WhereStreamOp

功能介绍

对流式数据进行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

  1. from pyalink.alink import *
  3. import pandas as pd
  5. useLocalEnv(1)
  7. df = pd.DataFrame([
  8.     ["a", 1, 1.1, 1.2],
  9.     ["b", -2, 0.9, 1.0],
  10.     ["c", 100, -0.01, 1.0],
  11.     ["d", -99, 100.9, 0.1],
  12.     ["a", 1, 1.1, 1.2],
  13.     ["b", -2, 0.9, 1.0],
  14.     ["c", 100, -0.01, 0.2],
  15.     ["d", -99, 100.9, 0.3]
  16. ])
  17. source = StreamOperator.fromDataframe(df, schemaStr='col1 string, col2 int, col3 double, col4 double')
  18. source.link(WhereStreamOp().setClause("col1='a'")).print()
  19. StreamOperator.execute()

Java 代码

  1. import org.apache.flink.types.Row;
  3. import com.alibaba.alink.operator.stream.StreamOperator;
  4. import com.alibaba.alink.operator.stream.source.MemSourceStreamOp;
  5. import org.junit.Test;
  7. import java.util.Arrays;
  8. import java.util.List;
  10. public class WhereStreamOpTest {
  12.     @Test
  13.     public void testWhereStreamOp() throws Exception {
  14.         List <Row> inputRows = Arrays.asList(
  15.             Row.of("a", 1, 1.1, 1.2),
  16.             Row.of("b", -2, 0.9, 1.0),
  17.             Row.of("c", 100, -0.01, 1.0),
  18.             Row.of("d", -99, 100.9, 0.1),
  19.             Row.of("a", 1, 1.1, 1.2),
  20.             Row.of("b", -2, 0.9, 1.0),
  21.             Row.of("c", 100, -0.01, 0.2),
  22.             Row.of("d", -99, 100.9, 0.3)
  23.         );
  24.         StreamOperator <?> source = new MemSourceStreamOp(inputRows,
  25.             "col1 string, col2 int, col3 double, col4 double");
  26.         StreamOperator <?> output = source.link(new WhereStreamOp().setClause("col1='a'"));
  27.         output.print();
  28.         StreamOperator.execute();
  29.     }
  30. }

运行结果

| col1 | col2 | col3 | col4 | | —- | —- | —- | —- |

| a | 1 | 1.1000 | 1.2000 |

| a | 1 | 1.1000 | 1.2000 |