R语言主成分分析

读入数据，观察结构

> data(attitude)
> head(attitude)
  rating complaints privileges learning raises critical advance
1     43         51         30       39     61       92      45
2     63         64         51       54     63       73      47
3     71         70         68       69     76       86      48
4     61         63         45       47     54       84      35
5     81         78         56       66     71       83      47
6     43         55         49       44     54       49      34
> str(attitude)
'data.frame':	30 obs. of  7 variables:
 $ rating    : num  43 63 71 61 81 43 58 71 72 67 ...
 $ complaints: num  51 64 70 63 78 55 67 75 82 61 ...
 $ privileges: num  30 51 68 45 56 49 42 50 72 45 ...
 $ learning  : num  39 54 69 47 66 44 56 55 67 47 ...
 $ raises    : num  61 63 76 54 71 54 66 70 71 62 ...
 $ critical  : num  92 73 86 84 83 49 68 66 83 80 ...
 $ advance   : num  45 47 48 35 47 34 35 41 31 41 ...
> dim(attitude)
[1]