Clustering analysis is a statistical analysis method

which aims to classify the data from their similarities. Based on road network topology，a new algorithm had been put forward to achieve the clustering analysis for points of interest(POI) in transportation field. The algorithm is that POI taken from point sets would be extend to the adjacent node and has a breadth of search along the direction of the network topology with limiting conditions of aggregating degree(α) and extending degree(β). POI those meet the conditions would be clustered together. At last

this algorithm is applied in the Guangzhou Pearl River Metro network to analysis pedestrian accessibility.