Question: Considering running the PCY algorithm on a dataset with 5 0 0 million baskets to count frequent pairs of items. Suppose each basket contains n
Considering running the PCY algorithm on a dataset with million baskets to count frequent pairs of items. Suppose each basket contains n items and there are d distinct itempairs amongst all of the baskets. Consider the following setup during the first pass of PCY: Besides keeping the counters for every singleton itemset observed during the first pass, we can still afford to store in main memory million integers, each of which is a bucket. Assume further that d is much larger than the total number of buckets available, ie d million. a marks As a function of n andor d what is the minimum support threshold s we can allow if the average count for a bucket should be no more than of the threshold? b marks Suppose that A B C D E and F are all the items under consideration. For a particular support threshold, the maximal frequent itemsets are A B D and C E What are all the other frequent itemsets?
Considering running the PCY algorithm on a dataset with million baskets to count frequent pairs of items. Suppose each basket contains n items and there are d distinct itempairs amongst all of the baskets. Consider the following setup during the first pass of PCY: Besides keeping the counters for every singleton itemset observed during the first pass, we can still afford to store in main memory million integers, each of which is a bucket. Assume further that d is much larger than the total number of buckets available, ie d million. a marks As a function of n andor d what is the minimum support threshold s we can allow if the average count for a bucket should be no more than of the threshold? b marks Suppose that A B C D E and F are all the items under consideration. For a particular support threshold, the maximal frequent itemsets are A B D and C E What are all the other frequent itemsets?
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