Java 类名：com.alibaba.alink.operator.batch.dataproc.StratifiedSampleBatchOp
Python 类名：StratifiedSampleBatchOp

功能介绍

本算子是对每个类别按照比例进行分层随机抽样。

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
withReplacement 是否放回 是否有放回的采样，默认不放回 Boolean false

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',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.     ])
  17. batchData = BatchOperator.fromDataframe(df, schemaStr='x1 string, x2 double, x3 double')
  18. sampleOp = StratifiedSampleBatchOp()\
  19.        .setStrataCol("x1")\
  20.        .setStrataRatios("a:0.5,b:0.5")
  22. batchData.link(sampleOp).print()

Java 代码

  1. import org.apache.flink.types.Row;
  3. import com.alibaba.alink.operator.batch.BatchOperator;
  4. import com.alibaba.alink.operator.batch.dataproc.StratifiedSampleBatchOp;
  5. import com.alibaba.alink.operator.batch.source.MemSourceBatchOp;
  6. import org.junit.Test;
  8. import java.util.Arrays;
  9. import java.util.List;
  11. public class StratifiedSampleBatchOpTest {
  12.     @Test
  13.     public void testStratifiedSampleBatchOp() throws Exception {
  14.         List <Row> df = 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.         BatchOperator <?> batchData = new MemSourceBatchOp(df, "x1 string, x2 double, x3 double");
  23.         BatchOperator <?> sampleOp = new StratifiedSampleBatchOp()
  24.             .setStrataCol("x1")
  25.             .setStrataRatios("a:0.5,b:0.5");
  26.         batchData.link(sampleOp).print();
  27.     }
  28. }

运行结果

| x1 | x2 | x3 | | —- | —- | —- |

| a | 0.0000 | 0.0000 |

| b | 9.5000 | 9.7000 |

| b | 9.1000 | 9.6000 |

| b | 9.3000 | 9.9000 |