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R でグラフ理論
library(igraph)
#エッジリストの作成
d <- data.frame(matrix(c( "s","a", "s","b", "a","b", "a","c", "a","d", "b","a", "b","c", "b","d",
"c","d", "c","e", "c","f", "d","a", "d","b", "d","f", "e","d", "e","z",
"f","e", "f","z"),nc=2,byrow=TRUE),stringsAsFactors=FALSE)
colnames(d) <- c("from","to")
#ノードリストの作成
vers <- data.frame(c("s","a","b","c","d","e","f","z"),stringsAsFactors=FALSE)
#グラフの作成
g <- graph.data.frame(d,directed=TRUE,vertices=vers)
#ウエイトの指定
E(g)$weight <- c(3,5,1,10,11,3,2,3,2,7,12,15,7,2,11,2,3,2)
#ノードの座標の指定
vs <- c(1,2); va <- c(3,3); vb <- c(3,1); vc <- c(5,3); vd <- c(5,1); ve <- c(7,3); vf <- c(7,1); vz <- c(9,2)
lay <- rbind(vs,va,vb,vc,vd,ve,vf,vz)
#プロット
par(mfrow=c(1,2),oma=c(0,0,0,0))
plot(g,layout=lay,vertex.label=V(g)$name,edge.label=E(g)$weight)
#最短経路の計算
spv <- shortest.paths(g, v=0,mode="out")
sp <- get.shortest.paths(g,from=0,to=7)
V(g)$color <- "lightblue"
V(g)$color[(unlist(sp)+1)] <- "red"
E(g)$width <- 1
E(g,path=unlist(sp))$width <- 3
plot(g,layout=lay,vertex.label=spv,edge.label=E(g)$weight)
shortest.jpg