Method for generating largest item set, method and system for analyzing scores based on Apriori

The invention discloses a method for generating the largest item set, and a method and system for analyzing scores based on Apriori. The method includes: 1. making a statistics of frequencies corresponding to all elements in an original item; 2. combining all the element in the original item to obtain a frequent item set; 3. when an item which is smaller than a preset support degree exists in the frequent item set, removing the item which is smaller than the preset support degree in the frequent item set, and otherwise reserving the frequent item set; and 4. comparing the number of elements in the frequent item set after Step 3 with a value obtained by subtracting 1 from the number of cycles: when the number of each existing element in the frequent item set is smaller than or equal to the number of cycles, removing an item where an element whose number is smaller than the value obtained by subtracting 1 from the number of cycles is, combining to form a new frequent item set to replace the frequent item set, retuning to Step 3, and adding 1 to the number of cycles; and 2) when the number of each existing elements in the frequent item set is equal to the number of cycles, combining all the elements in the frequent item set to obtain the largest item set. The method reduces I/O overhead of a computer system.