Mining positive and negative association rules in Hadoop's MapReduce environment

In this paper, we mine positive and negative rules from Big Data in Hadoop's MapReduce Environment. Positive association rule mining finds items that are positively co-related whereas negative association rule mining finds items that are negatively correlated. Positive association rule mining has been traditionally used to mine association rules, but negative association rule mining also has many applications, including the building of efficient decision support systems, for crime data analysis [2], in the health care sector [1], etc. In this paper, we mine positive and negative association rules using the Apriori algorithm in the Big Data environment using Hadoop's MapReduce environment. Positive association rules are in the form X→Y, which has support s in a transaction set D if s% of the transactions in D contain X U Y. A negative association rule is in the form X → ┐ Y or ┐ X → Y or ┐ X → ┐ Y where X ∩ Y = Ø. X → ┐ Y refers to X occurring in the absence of Y; ┐ X → Y refers to Y occurring in the absence of X; ┐ X → ┐ Y means not X and not Y. For positive association rules: Support (X → Y) refers to the percentage of transactions where itemsets X and Y co-exist in a dataset. Confidence (X → Y) is taken to be the conditional probability, P(X|Y). That is, the percentage of transactions containing X that also contain Y. Support of the negative association rules will be form: Supp(X → ┐ Y) > min_supp; Supp(┐ X → Y) > min_supp; Supp(┐ X → ┐ Y) > min_supp. Confidence of negative association rules will be in the form: Conf(X → ┐ Y) > min_supp; Conf(┐ X → Y) > min_supp; Conf(┐ X → ┐ Y) > min_supp. In MapReduce, we scan the dataset and create 1-itemsets in one MapReduce job and then use this 1-itemset to create 2-itemsets in another MapReduce job. In the last map job, the calculation of positive and negative association rules as well as the calculations of support, confidence and lift are performed. Therefore, in essence, we use three map and two reduce jobs. The main contribution of this work is in presenting how the apriori algorithm can be used to extract negative association rules from Big Data and how it can be executed efficiently on MapReduce.