“…To measure the built environment, the 2016 Nanjing POI data, which were obtained from the Baidu map, were also used in this study. POI data are a kind of point data representing real geographical entities and include spatial information such as latitude and longitude and addresses, and attribute information such as name and category [39]. The data collected for this study include information about the boundaries of the county and district, urban roads, parks, metro stations, bus stations, public bicycle stations, parking lots, financial service areas, commercial buildings, retail industries, hotels, recreation, medical services, research and education, and corporate and residential communities.…”