我觉得你漏掉了一个边缘列表graph_from_data_frame所需要的数据。

library(tidyverse)
library(igraph)
(start <- tibble::tribble(
   ~actor.1, ~actor.2, ~actor.3, ~actor.4,
     "Mary",   "Anna",    "bob",   "jack",
     "Lucy",   "Sara",    "bob",  "Alice",
  "Nicolas",    "rob",       NA,       NA,
   "Angela",   "Mary",   "Anna",       NA
  ) |> mutate(rel=row_number()))

(longlist <- pivot_longer(start,
                          cols=-rel) |> na.omit()|>
    mutate(value=factor(value)) |> select(-name))

(edgelist <- left_join(longlist,
                       longlist,
                       by=join_by(rel == rel),
                       multiple="all") |> filter(value.x!=value.y) |>
    relocate(rel,.after=everything()))

ig <- graph_from_data_frame(edgelist)
matrix <- get.adjacency (ig)