如何理解R语言做网络图的分析

1、一个包括一列数据的数据框，每一行是各个节点的名称

2、一个包含两列数据的数据框，每一行代表节点节点之间的连线

> nodes<-data.frame(node=c("A","B","C","D"))
> edges<-data.frame(node1=c("A","A","A","B","B","C"),
+                   node2=c("B","C","D","C","D","D"))
> nodes
  node
1    A
2    B
3    C
4    D
> edges
  node1 node2
1     A     B
2     A     C
3     A     D
4     B     C
5     B     D
6     C     D
>

library(ggraph)
library(igraph)
net<-graph_from_data_frame(d=edges,vertices = nodes,directed = F)
ggraph(net)+
  geom_edge_link()+
  geom_node_point()

给节点添加一列分组信息，给每个节点一个数值，用来映射节点大小。

nodes$Group<-c("group_1","group_1","group_2","group_2")
nodes$Size<-c(5,15,10,18)
nodes$Name<-nodes$node

给每条边添加颜色和粗细的映射数值

edges$color<-sample(seq(0,1,by=0.01),6)
edges$width<-sample(1:100,6)

net<-graph_from_data_frame(d=edges,vertices = nodes,directed = F)
ggraph(net)+
  geom_edge_link(aes(edge_width=width,edge_color=color))+
  geom_node_point(aes(size=Size,color=Group))+
  geom_node_text(aes(label=Name))

边的渐变色深蓝到浅蓝不太好看，换！加上语句

scale_edge_color_continuous(low = "cyan",high = "red")

ggraph(net)+
  geom_edge_link(aes(edge_width=width,edge_color=color))+
  geom_node_point(aes(size=Size,color=Group))+
  geom_node_text(aes(label=Name))+
  scale_edge_color_continuous(low = "cyan",high = "red")

每个节点的点太小了，增大！加上语句

scale_size_area(max_size = 30)

ggraph(net)+
  geom_edge_link(aes(edge_width=width,edge_color=color))+
  geom_node_point(aes(size=Size,color=Group))+
  geom_node_text(aes(label=Name))+
  scale_edge_color_continuous(low = "cyan",high = "red")+
  scale_size_area(max_size = 30)

点的图例太大了，占了其他图例的位置，不要他了！加上语句

guides(size=F)

ggraph(net)+
  geom_edge_link(aes(edge_width=width,edge_color=color))+
  geom_node_point(aes(size=Size,color=Group))+
  geom_node_text(aes(label=Name))+
  scale_edge_color_continuous(low = "cyan",high = "red")+
  scale_size_area(max_size = 30)+
  guides(size=F)

这里遇到一个问题是：有没有办法改变图例中点的大小呢？

新学到的：还可以改变图例的前后顺序，添加语句

guides(color=guide_legend(order=3))

ggraph(net)+
  geom_edge_link(aes(edge_width=width,edge_color=color))+
  geom_node_point(aes(size=Size,color=Group))+
  geom_node_text(aes(label=Name))+
  scale_edge_color_continuous(low = "cyan",high = "red")+
  scale_size_area(max_size = 30)+
  guides(size=F)+
  guides(color=guide_legend(order=3))

虽然点大小的图例删掉了，但是他应该还是站着位置呢！如果想要把颜色图例设置为最后可能得把order设置为4。

有的节点超出了绘图边界，可以通过修改x和y轴的范围来调整，加上命令

theme_bw()就可以显示出坐标轴的范围

ggraph(net)+
  geom_edge_link(aes(edge_width=width,edge_color=color))+
  geom_node_point(aes(size=Size,color=Group))+
  geom_node_text(aes(label=Name))+
  scale_edge_color_continuous(low = "cyan",high = "red")+
  scale_size_area(max_size = 30)+
  guides(size=F)+
  guides(color=guide_legend(order=3))+
  theme_bw()+
  xlim(-0.8,0.8)+ylim(-0.8,0.8)