Evolution Characteristics of Advanced Nonferrous Metal Industry Patent Cooperation Network in China from the Perspective of Multilayer Network

Table 3

Structural characteristic values of invention patent cooperation networks in different stages of China’s advanced nonferrous metal industry.

Index	Stage 1: 2002–2007	Stage 2: 2008–2011	Stage 3: 2012–2016	Stage 4: 2017–2020
Network size	275	1025	2088	2567
Number of network edge	254	988	2338	3404
Network diameter	6	11	14	16
Graph density	0.006	0.002	0.001	0.001
Average clustering coefficient	0.738	0.721	0.713	0.732
Average path length	2.77	5.03	4.99	5.29