Automatic generation of initial value k to apply k-means method for text documents clustering

Retrieving relevant text documents on a topic from a large document collection is a challenging task. Different clustering algorithms are developed to retrieve relevant documents of interest. Hierarchical clustering shows quadratic time complexity of O(n²) for n text documents. K-means algorithm has a time complexity of O(n) but it is sensitive to the initial randomly selected cluster centres, giving local optimum solution. Global k-means employs the k-means algorithm as a local search procedure to produce global optimum solution but shows polynomial time complexity of O(nk) to produce k clusters. In this paper, we propose an approach of clustering text documents that overcomes the drawback of k-means and global k-means and gives global optimal solution with time complexity of O(lk) to obtain k clusters from initial set of l starting clusters. Experimental evaluation on Reuters newsfeeds (Reuters-21578) shows clustering results (entropy, purity, F-measure) obtained by proposed method comparable with k-means and global k-means.