Java 类名：com.alibaba.alink.operator.stream.dataproc.StratifiedSampleStreamOp
Python 类名：StratifiedSampleStreamOp

功能介绍

分层采样是对每个类别进行随机抽样。

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 | | —- | —- | —- | —- | —- | —- | —- |

| strataCol | 分层列 | 分层列 | String | ✓ | | |

| strataRatios | 采用比率 | 采用比率, eg, a:0.1,b:0.3 | String | ✓ | | |

| strataRatio | 采用比率 | 采用比率 | Double | | | -1.0 |

代码示例

Python 代码

  1. from pyalink.alink import *
  3. import pandas as pd
  5. useLocalEnv(1)
  7. df_data = pd.DataFrame([
  8.         ['a',0.0,0.0],
  9.         ['a',0.2,0.1],
  10.         ['b',0.2,0.8],
  11.         ['b',9.5,9.7],
  12.         ['b',9.1,9.6],
  13.         ['b',9.3,9.9]
  14.     ])
  16. streamData = StreamOperator.fromDataframe(df_data, schemaStr='x1 string, x2 double, x3 double')
  17. sampleStreamOp = StratifiedSampleStreamOp()\
  18.        .setStrataCol("x1")\
  19.        .setStrataRatios("a:0.5,b:0.5")
  21. sampleStreamOp.linkFrom(streamData).print()
  23. 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.dataproc.StratifiedSampleStreamOp;
  5. import com.alibaba.alink.operator.stream.source.MemSourceStreamOp;
  6. import org.junit.Test;
  8. import java.util.Arrays;
  9. import java.util.List;
  11. public class StratifiedSampleStreamOpTest {
  12.     @Test
  13.     public void testStratifiedSampleStreamOp() throws Exception {
  14.         List <Row> df_data = Arrays.asList(
  15.             Row.of("a", 0.0, 0.0),
  16.             Row.of("a", 0.2, 0.1),
  17.             Row.of("b", 0.2, 0.8),
  18.             Row.of("b", 9.5, 9.7),
  19.             Row.of("b", 9.1, 9.6),
  20.             Row.of("b", 9.3, 9.9)
  21.         );
  22.         StreamOperator <?> streamData = new MemSourceStreamOp(df_data, "x1 string, x2 double, x3 double");
  23.         StreamOperator <?> sampleStreamOp = new StratifiedSampleStreamOp()
  24.             .setStrataCol("x1")
  25.             .setStrataRatios("a:0.5,b:0.5");
  26.         sampleStreamOp.linkFrom(streamData).print();
  27.         StreamOperator.execute();
  28.     }
  29. }

运行结果

| x1 | x2 | x3 | | —- | —- | —- |

| b | 9.3 | 9.9 |

| a | 0.0 | 0.0 |

| b | 0.2 | 0.8 |