Common power laws for cities and spatial fractal structures
Common power laws for cities and spatial fractal structures
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DOI：
10.1073/pnas.1913014117
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发表时间：
2020-03-24
影响因子：
11.1
通讯作者：
Hsu, Wen-Tai
中科院分区：
文献类型：
--
作者：
Mori, Tomoya;Smith, Tony E.;Hsu, Wen-Tai
众所周知，在许多国家，城市规模分布都可以很好地近似于幂律分布。但这种分布在其他空间尺度上也有意义，例如在一个国家的某些地区。利用来自中国、法国、德国、印度、日本和美国的数据，我们首先证明，大城市的空间分布比仅仅依靠偶然因素所预期的要大得多。接下来，我们构建国家的空间层次结构，首先使用给定数量的最大城市作为单元格中心划分地理空间，然后在每个单元格内递归地继续这种划分过程。我们发现，城市规模分布在这些空间层次结构的不同部分表现出幂律，再次，远比预期的机会更相似，这表明存在一个空间分形结构。
City-size distributions are known to be well approximated by power laws across a wide range of countries. But such distributions are also meaningful at other spatial scales, such as within certain regions of a country. Using data from China, France, Germany, India, Japan, and the United States, we first document that large cities are significantly more spaced out than would be expected by chance alone. We next construct spatial hierarchies for countries by first partitioning geographic space using a given number of their largest cities as cell centers and then continuing this partitioning procedure within each cell recursively. We find that city-size distributions in different parts of these spatial hierarchies exhibit power laws that are, again, far more similar than would be expected by chance alone-suggesting the existence of a spatial fractal structure.