Research On The Transformation From Central City System To Network City System

The spatial organization relationship in the urban system is an important content of urban geography,urban and rural planning and other disciplines.As one of the basic guiding theories of urban system planning,the premise of homogeneity and non-discrimination makes central place theory inadaptable in the current Chinese urban system research and planning practice.With the in-depth development of regional integration within urban agglomerations,the links at the micro level of the city continue to increase,and multi-level network systems are gradually becoming a better choice for the spatial layout and development of urban agglomerations.Based on the comparative study of central place system and urban network system,re-recognize the urban relationship and spatial organization under traditional central place theory,and identify the special functions and status of the professional city in urban agglomeration network system.This is of great significance for improving the multi-level network space development model and improving the scientificalness of the research on urban systems with Chinese characteristics.This article uses Python to crawl the commercial POI data of Yangtze River Delta,Pearl River Delta,and Beijing-Tianjin-Hebei Urban Agglomerations in Amap in April,2020.Use plane kernel density analysis method,contour extraction method and neighborhood analysis method to identify and extract commercial areas and commercial centers.According to the constructed index system of the central place rating system,K-Means cluster analysis method is used to classify the commercial centers,and on this basis,the scale deduction is carried out.Use the Voronoi diagram to draw the spatial organization structure of the commercial center,and compare the fit degree of the commercial center of different urban agglomerations.According to the commercial district extracted from Delaunay triangulation in computational geometry,and based on the optimal search distance of kernel density analysis,the network model of urban agglomeration commercial districts is constructed.By calculating the evaluation indicators of the network model,the network systems of the commercial districts of different urban agglomerations are compared,and a series of professional network nodes are identified.The main research results and conclusions are as follows:(1)The commercial centers in Yangtze River Delta,Pearl River Delta,Beijing-Tianjin-Hebei Urban Agglomerations and "3 Provinces and 1 City" in Yangtze River Delta can be divided into 4 levels.The quantity distribution conforms to the central place theoretical hierarchy,but it is different from the ideal hierarchy.In terms of spatial distribution,the hexagonal structure of the commercial centers has distortion and offset.(2)The level of social and economic development and administrative hierarchy are important factors affecting the commercial center system of urban agglomerations.The order of the fitting degree of the center system is Yangtze River Delta,Pearl River Delta,Beijing-Tianjin-Hebei,and Yangtze River Delta is Shanghai,Jiangsu,Anhui,and Zhejiang.The central region system of Jiangsu and Zhejiang has gradually collapsed,but Anhui has become more stable.In terms of spatial structure,Yangtze River Delta has "one superpower and multiple powers",Pearl River Delta has dual-core leadership,but Beijing-Tianjin-Hebei tends to be loose.(3)Based on the optimal search distance of nuclear density analysis,the network model system constructed has spatial selectivity and imbalance,and can conduct spatial assessment of the distribution of urban agglomeration commercial districts.In terms of network structure,Shanghai's core,periphery and isolation coexist,Jiangsu and Zhejiang are dense and complex,but Anhui is sparse and simple.The network of Yangtze River Delta is mature,the structure of Pearl River Delta is more compact,but Beijing-Tianjin-Hebei is in a loosely emerging state.(4)According to the evaluation indicators of the network model,the low-level network of Jiangsu,Zhejiang and Shanghai has been continuously formed,and the urban system has been transformed from central city system to network city system.The central city system of Anhui still exists and is in the initial stage of transformation.The potential network of connections in Yangtze River Delta continues to develop,Pearl River Delta has the most closely connected network,but Beijing-Tianjin-Hebei has a lower degree of closeness.According to the identified professional network nodes,Yangtze River Delta and "3 Provinces and 1 city" have more potential interaction areas.Pearl River Delta has stronger interactions in the west wing than the east wing,but there are missing potential functional nodes in Beijing-Tianjin-Hebei.(5)Taking the commercial district as an example,both central place theory and urban network system can identify the urban spatial organization relationship in the urban agglomeration,and can complement each other.Central place theory emphasizes centrality,primacy and hierarchy,while network system emphasizes equality,functionality and complementarity.Central city system has idealized premises and one-sided pursuit of exclusive spatial structure,and is gradually transforming into a new network system that emphasizes multi-level interaction.