Table 2 The changing trend of three representative generalized correlation dimensions and their reflected geographic information.

Capacity dimension D₀

Space-filling degree

Quasi S-shaped curve. First rise, then tend to be stable

The spatial distribution range of COVID-19 pandemic was expanded first and then converged

Information dimension D₁

Spatial uniformity

Firstly, it rose rapidly and then decreased gradually

The spatial differences of COVID-19 pandemic were first reduced and then enlarged

Correlation dimension D₂

Spatial dependence

Firstly, it rose rapidly and then decreased gradually

The spatial correlation of COVID-19 pandemic were first reduced and then enlarged