如何解决我应该在同一个类中实现这两个接口吗?
我有两个接口:Normalizer
和 ScoringSummary
如下:
-
标准化器:
public interface Normalizer { /** * Accepts a <code>csvPath</code> for a CSV file,perform a Z-Score normalization against * <code>colToStandardize</code>,then generate the result file with additional scored column to * <code>destPath</code>. * * @param csvPath path of CSV file to read * @param destPath path to which the scaled CSV file should be written * @param colToStandardize the name of the column to normalize * @return */ ScoringSummary zscore(Path csvPath,Path destPath,String colToStandardize); /** * Accepts a <code>csvPath</code> for a CSV file,perform a Min-Max normalization against * <code>colToNormalize</code>,then generate the result file with additional scored column to * <code>destPath</code>. * * @param csvPath path of CSV file to read * @param destPath path to which the scaled CSV file should be written * @param colToNormalize the name of the column to normalize * @return */ ScoringSummary minMaxScaling(Path csvPath,String colToNormalize); }
-
评分总结:
public interface ScoringSummary { public BigDecimal mean(); public BigDecimal standardDeviation(); public BigDecimal variance(); public BigDecimal median(); public BigDecimal min(); public BigDecimal max(); }
这是来自 TDD 的一个函数:
@Test
public void givenMarksCSVFileToScale_whenMarkColumnIsZScored_thenNewCSVFileIsGeneratedWithAdditionalZScoreColumn() throws IOException {
String filename = "marks.csv";
Path induction = Files.createTempDirectory("induction");
String columnName = "mark";
Path csvPath = induction.resolve(filename);
Path destPath = induction.resolve("marks_scaled.csv");
copyFile("/marks.csv",csvPath);
Assertions.assertTrue(Files.exists(csvPath));
Normalizer normalizer = normalizer();
ScoringSummary summary = normalizer.zscore(csvPath,destPath,columnName);
Assertions.assertNotNull(summary,"the returned summary is null");
Assertions.assertEquals(new BigDecimal("66.00"),summary.mean(),"invalid mean");
Assertions.assertEquals(new BigDecimal("16.73"),summary.standardDeviation(),"invalid standard deviation");
Assertions.assertEquals(new BigDecimal("280.00"),summary.variance(),"invalid variance");
Assertions.assertEquals(new BigDecimal("65.00"),summary.median(),"invalid median");
Assertions.assertEquals(new BigDecimal("40.00"),summary.min(),"invalid min value");
Assertions.assertEquals(new BigDecimal("95.00"),summary.max(),"invalid maximum value");
Assertions.assertTrue(Files.exists(destPath),"the destination file does not exists");
Assertions.assertFalse(Files.isDirectory(destPath),"the destination is not a file");
List<String> generatedLines = Files.readAllLines(destPath);
Path assertionPath = copyFile("/marks_z.csv",induction.resolve("marks_z.csv"));
List<String> expectedLines = Files.readAllLines(assertionPath);
assertLines(generatedLines,expectedLines);
}
如何在一个java类中实现这两个接口? 我是否需要任何依赖项或其他框架来解析 CSV?
解决方法
您不一定需要依赖项或框架来处理 CSV 数据。但是,使用现有库比自己实现所有内容要容易得多。
实现这两个接口有很多不同的方法。您的实施只需要履行他们的合同。以下是一些示例:
两个独立的类
public class NormalizerImplSplit implements Normalizer {
@Override
public ScoringSummary zscore(Path csvPath,Path destPath,String colToStandardize) {
// process CSV and store summary results
ScoringSummaryImpl summary = new ScoringSummaryImpl();
summary.setMean(new BigDecimal("66.00"));
// return summary object
return summary;
}
// other method of Normalizer
}
public class ScoringSummaryImpl implements ScoringSummary {
private BigDecimal mean;
public void setMean(BigDecimal mean) {
this.mean = mean;
}
@Override
public BigDecimal mean() {
return this.mean;
}
// other methods of ScoringSummary
}
Normalizer
实现与嵌套的 ScoringSummary
实现
public class NormalizerImplNested implements Normalizer {
@Override
public ScoringSummary zscore(Path csvPath,String colToStandardize) {
// process CSV and store summary results
ScoringSummaryImpl summary = new ScoringSummaryImpl();
summary.setMean(new BigDecimal("66.00"));
// return summary object
return summary;
}
// other method of Normalizer
public static class ScoringSummaryImpl implements ScoringSummary {
private BigDecimal mean;
private void setMean(BigDecimal mean) {
this.mean = mean;
}
@Override
public BigDecimal mean() {
return this.mean;
}
// other methods of ScoringSummary
}
}
单个类实现 Normalizer
和 ScoringSummary
public class NormalizerImpl implements Normalizer,ScoringSummary {
private BigDecimal mean;
@Override
public ScoringSummary zscore(Path csvPath,String colToStandardize) {
// process CSV and store summary results
this.mean = new BigDecimal("66.00");
// return this instance since ScoringSummary is also implemented
return this;
}
@Override
public BigDecimal mean() {
return this.mean;
}
// other methods of the two interfaces
}
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