igraph 如何根据条件改变节点大小和边框颜色/厚度

Question

对于数据框

df <- data.frame(g1=c("x1","x2","x2","x3","x4","x5","x5","x3"),
                               g2=c("y1","y4","y2","y4","y3","y4","y5","y4"), 
                               g1value=c(1,2,2,3,4,5,5,3),
                               g2value=c(2,4,2,4,5,4,NA, 4),
                               stringsAsFactors = FALSE)

library(igraph)
g=graph.data.frame(df, directed=F)
plot(g)

我应该如何指定节点的大小，使得每个x节点的大小对应g1value，y节点对应g2value（如果节点大小为na，则忽略该节点）？

以及如何根据条件改变节点边框颜色或粗细，例如当节点为 x2 时？

如果节点很多，而且绘图结果很拥挤，无论如何要隔开？

谢谢。

Answer 1

这是一个开始 - 您可以将不同大小和颜色的向量传递给 plot.igraph 的参数，以便它们应用于不同的节点。它们按V(g)$name的顺序给出。

# tweaking your data to increase node size
df <- data.frame(g1=c("x1","x2","x2","x3","x4","x5","x5","x3"),
                 g2=c("y1","y4","y2","y4","y3","y4","y5","y4"), 
                 g1value=10*c(1,2,2,3,4,5,5,3),
                 g2value=10*c(2,4,2,4,5,4,NA, 4),
                 stringsAsFactors = FALSE)

library(igraph)

g <- graph.data.frame(df[,1:2], directed=F)

# create a vector of vertex sizes conditional on g*values in df
# set missing values to size 0 
r <- data.frame(g=c(df$g1, df$g2), value=c(df$g1value, df$g2value))
sz <- r$value[match(V(g)$name, r$g)]
sz[is.na(sz)] <- 0 

# create a vertor of border colours conditional on node type
bd <- ifelse(grepl("x", V(g)$name), "red", NA) 

# add the size and border colour vectors to relevant plot arguments     
plot(g, vertex.size=sz, vertex.frame.color=bd)

igraph 有很好的帮助页面，请参阅 ?igraph::layout 了解图形布局选项，?plot.igraph 和 ?igraph.plotting 了解一些绘图选项/参数。

边框宽度请关注this link。