Alternative Approaches to Parallel GIS Processing

clusterGIS-chaining.c

/* remove all residential parcels */
parcel = parcels->data;
head = &(parcels->data);
while(parcel != NULL) {
        if(strncmp(parcel->data[2], "R", 1) == 0) {
                head = &(parcel->next);
                parcel = parcel->next;
        } else {
                *head = parcel->next;
                clusterGIS_Free_record(parcel);
                parcel = *head;
        }
}

/* Find the min distance */
employer = employers->data;
min = malloc(sizeof(double)*2);
global_min = malloc(sizeof(double)*2);
output = clusterGIS_Create_dataset();
while(employer != NULL) {

        /* find the local min */
        parcel = parcels->data;
        GEOSDistance(employer->geometry, parcel->geometry, &min_distance);
        min_distance_parcel = parcel;
        while(parcel != NULL) {
                if(strncmp(employer->data[2], parcel->data[2], 1) == 0) {
                        GEOSDistance(employer->geometry, parcel->geometry, &distance);
                        if(distance < min_distance) {
                                min_distance = distance;
                                min_distance_parcel = parcel;
                        }
                }
                parcel = parcel->next;
        }

        /* find the global min */
        min[0] = atoi(min_distance_parcel->data[0]);
        min[1] = min_distance;
        MPI_Allreduce(min, global_min, 2, MPI_DOUBLE, min_distance_op, parcels_comm);

        /* Add the min to the output dataset using front insertion*/
        sprintf(output_csv, "\"%s\",\"%d\"\n", employer->data[0], (int) global_min[0]);
        start = 0;
        output_record = clusterGIS_Create_record_from_csv(output_csv, &start);
        output_record->next = output->data;
        output->data = output_record;

        employer = employer->next;
}

clusterGIS-create.c

if(rank == 0) {
        int start = 0;
        record = clusterGIS_Create_record_from_csv("97123897,POINT(0 0),C\n", &start);
        record->next = dataset->data;
        dataset->data = record;
}

clusterGIS-filter.c

box = GEOSWKTReader_read(reader, "POLYGON((-112.0859375 33.4349975585938,-112.0859375 33.4675445556641,-112.059799194336 33.4675445556641,-112.059799194336 33.4349975585938,-112.0859375 33.4349975585938))");

record = dataset->data;
head = &(dataset->data);
/* keep records that match the criteria, otherwise delete them */
while(record != NULL) {
        char intersects;

        intersects = GEOSIntersects(record->geometry, box);

        if(intersects == 1) { /* record overlaps with box */
                head = &(record->next);
                record = record->next;
        } else { /* no overlap */
                *head = record->next;
                clusterGIS_Free_record(record);
                record = *head;
        }
}

clusterGIS-read.c

record = dataset->data;
head = &(dataset->data);
/* keep records that match the criteria, otherwise delete them */
while(record != NULL) {
        if(atoi(record->data[0]) == 1008130) {
                head = &(record->next);
                record = record->next;
        } else {
                *head = record->next;
                clusterGIS_Free_record(record);
                record = *head;
        }
}

clusterGIS-update.c

record = dataset->data;
/* keep records that match the criteria, otherwise delete them */
while(record != NULL) {
        if(atoi(record->data[0]) == 1008130) {
                record->data[2] = "C";
        }


        record = record->next;
}