Algorithm 2: STDF IoT-based Data Fusion Manager.
Input: HashMap ‘HC’ of key: source id and value: Arraylist of data units Output: HashMap ‘Final-HC’ of key: source id and value: 2D Arraylist of location ID & data unit
1  2  3  4  5  6  7     8  9  10  11     12  13     14  15  16  17  18  19  20  21  22  23  24     25  26  27	Begin   Initialize Clustered_HC as an empty HashMap//the HashMap to retain location IDs clustering results   For each key in HC//loop for all received source IDs   Initialize Centroids_List as an empty Arraylist   Initialize data_units_List with the current source ID’s data units   For each data unit ‘D’ in data_units_List//loop for all data units of the current source ID   If (location ID of ‘D’ is not in Centroids_List) then//check if the location ID of the current   data unit exists in the centroids list   {Add locationID of ‘D’ to Centroids_List}//add location ID if it does not exist}   End if   End for    Cluster with K-means using the current Centroids_List and data_units_List//apply clustering on    the current source ID’s data units using its current centroids    Add key to Clustered_HC//retain the current source ID in the HashMap    Add clustered data units to Clustered_HC//retain the resultant clustered data units for the    current source ID in the HashMap   End for   Initialize Final-HC as an empty HashMap//the HashMap used for data fusion   For each key in Clustered_HC//loop for all source IDs   Initialize ArrayList Updated-Tree as an empty Arraylist   Initialize ArrayList TAG-Tree with the clustered data units of the current source ID   For each locationID ‘loc’ in TAG-Tree//loop for all location IDs of current source ID   Initialize data_units_List with the data units of the current ‘loc’   Get the ‘Freshest data unit’ with the minimum generation time in data_units_list   Add the current ‘loc’ and its ‘Freshest data unit’ in Updated-Tree   End for    Add the current key and its Updated-Tree to Final-HC//retain the aggregated results on all location    IDs of the current source ID in the final HashMap   End for   Return Final-HC//return a HashMap of key: source ID and values: location IDs and freshest data units   End