Question

我有一个无方向的论文网络，它们相互引用。我想找到具有“出度”（即引用了一篇论文）但没有“入度”（任何人都未引用）的论文/节点/顶点。

这似乎是一个非常简单的问题，但我无法在堆栈溢出/互联网的任何地方找到答案。

谢谢您的帮助！

编辑：举个例子，具有单个入度而没有出度的边列表如下所示：

Paper1 -> Paper3
Paper2 -> Paper3
Paper4 -> Paper1
Paper1 -> Paper4
Paper5 -> Paper1
Paper6 -> Paper4

在此示例中，我只想知道Paper5和Paper6的身份，它们引用了一篇论文，但未引用。它不需要在边缘列表中（尽管也可以）。因此，期望的输出是：

identified_papers <- c("Paper5", "Paper6")

Answer 1

一旦您以适当的格式（例如，边缘列表：

from <- c("Paper1", "Paper2", "Paper4", "Paper1", "Paper5", "Paper6")
to <- c("Paper3", "Paper3", "Paper1", "Paper4", "Paper1", "Paper4")
edgelist <- cbind(from, to)

> edgelist
     from     to      
[1,] "Paper1" "Paper3"
[2,] "Paper2" "Paper3"
[3,] "Paper4" "Paper1"
[4,] "Paper1" "Paper4"
[5,] "Paper5" "Paper1"
[6,] "Paper6" "Paper4"

使用igraph可以从edgelist生成图形

library(igraph)
g <- graph_from_edgelist(edgelist)

使用degree函数以获取学位，并通过设置mode参数来指定是否计算学位或学位：

> degree(g, mode = "in")
  Paper1 Paper3 Paper2 Paper4 Paper5 Paper6 
     2      2      0      2      0      0 

> degree(g, mode = "out")
  Paper1 Paper3 Paper2 Paper4 Paper5 Paper6 
     2      0      1      1      1      1

从那里可以组合which内的查询条件以满足要求，并使用names提取相应的论文：

hits <- which(degree(g, mode = "in") == 0 & degree(g, mode = "out") == 1)
identified_papers <- names(hits)

> identified_papers
  [1] "Paper2" "Paper5" "Paper6"

我希望这会有所帮助。

如何在图中找到具有一个度但没有度的顶点？

1 个答案: