Apriori - 关联规则

Question

我已将apriori应用于我的帧矩阵。但是我得到的规则只包含一个字母。为什么规则只创建一个字母而不是单词？

frame_matrix:

     bazinda  yapilan  ragmen  yuklemesi   
  0    0        1        1       1                  
  1    0        0        1       0 
  2    2        0        0       1 

 rules = apriori(frame_matrix)   
 print "rules:", rules


 rules: ([[frozenset(['i'])], []], {frozenset(['f']): 0.12698412698412698, frozenset(['U']): 0.015873015873015872,