**Input:** training set , selected feature number |

**Output:** top features in |

() For each category |

() Compute the total term frequency of all terms in category |

() End For |

() For each term |

() Compute the total document frequency of a term in all categories |

() For each category |

() Compute the term frequency of a term in category |

() Compute the document frequency of a term in category |

() End For |

() End For |

() For each term |

() For each category |

() Compute the significance of a term in category |

() End For |

() End For |

() For each term |

() Compute the value of |

() End For |

() Rank all terms descendingly based on |

() Selest top terms as features |