Question

我正在使用weka进行主成分分析，但结果一定是错误的。

我的实例如下：

40.4,24.7,7.2,6.1,8.3,8.7,2.442,20
25,12.7,11.2,11,12.9,20.2,3.542,9.1
13.2,3.3,3.9,4.3,4.4,5.5,0.578,3.6
22.3,6.7,5.6,3.7,6,7.4,0.176,7.3
34.3,11.8,7.1,7.1,8,8.9,1.726,27.5
35.6,12.5,16.4,16.7,22.8,29.3,3.017,26.6
22,7.8,9.9,10.2,12.6,17.6,0.847,10.6
48.4,13.4,10.9,9.9,10.9,13.9,1.772,17.8
40.6,19.1,19.8,19,29.7,39.6,2.449,35.8
24.8,8,9.8,8.9,11.9,16.2,0.789,13.7
12.5,9.7,4.2,4.2,4.6,6.5,0.874,3.9
1.8,0.6,0.7,0.7,0.8,1.1,0.056,1
32.3,13.9,9.4,8.3,9.8,13.3,2.126,17.1
38.5,9.1,11.3,9.5,12.2,16.4,1.327,11.6
26.2,10.1,5.6,15.6,7.7,30.1,0.126,25.9

我的Java代码如下：

PrincipalComponents pca = new PrincipalComponents();
pca.buildEvaluator(instances);
pca.setVarianceCovered(0.9);
instances=pca.transformedData(instances);
System.out.println(instances);

结果如下：

-0.76617,2.661828，-0.543741,0
-0.970913,0.436367,1.69961,0
2.881824，-0.434979,0.32666,0
2.202041，-0.118079，-0.265614,0
-0.055269,0.917633，-0.825503,0
-3.389144，-0.661234,0.756936,0
0.326235，-0.94073,0.256852,0
-1.020299,0.939242，-0.408135,0
-5.193605，-0.979272，-0.020702,0
0.337214，-0.689053，-0.018816,0
2.413215,0.213961,0.314493,0
4.426397，-0.617956,0.288353,0
-0.373545,0.837791,0.108058,0
-0.347075，-0.059153,0.119701,0
-0.470905，-1.506368，-1.788153,0

但是我确信正确的结果如下：

0.76617,2.661828,0.543741,0
0.970913,0.436367，-1.69961,0
-2.881824，-0.434979，-0.32666,0
-2.202041，-0.118079,0.265614,0
0.055269,0.917633,0.825503,0
3.389144，-0.661234，-0.756936,0
-0.326235，-0.94073，-0.256852,0
1.020299,0.939242,0.408135,0
5.193605，-0.979272,0.020702,0
-0.337214，-0.689053,0.018816,0
-2.413215,0.213961，-0.314493,0
-4.426397，-0.617956，-0.288353,0
0.373545,0.837791，-0.108058,0
0.347075，-0.059153，-0.119701,0
0.470905，-1.506368,1.788153,0

第一列和第三列（第一主成分和第三主成分）的符号（正数或负数）颠倒。

我已经在stackoverflow上搜索了我的错误的线索，但是我找不到我的错误，所以有人可以找出我的代码或weka代码有什么问题吗？

Answer 1

主成分分析基于找到数据集的特征向量和特征值eigenvectors are not unique-或换句话说，the definition of eigenvector is ambidextrous。

用PCA术语来说，您可以否定任何主要组成部分的所有得分，只要您对加载进行相应的更改即可。

您从哪里获得“正确结果”？看起来好像是恰好使用了与Weka不同的约定的程序或程序包。

weka的主成分分析返回错误的实例

1 个答案: