以下是链接结构:
structure(list(from = c("Alabama", "Alabama", "Alabama", "Alabama", "Alabama", "Alabama"), to = c("Alaska", "Arizona", "Arkansas", "California", "Colorado", "Connecticut"), weight = c(423L, 894L, 2057L, 3045L, 2328L, 1102L)), row.names = c(NA, 6L), class = "data.frame")
structure(list(State = c("Hawaii", "Alaska", "South Dakota", "Maine", "Colorado", "Vermont"), Well.Being.Score = c(65.2, 64, 63.7, 63.6, 63.5, 63.5), Social.Rank = c(46L, 1L, 29L, 18L, 21L, 5L), Financial.Rank = c(1L, 2L, 3L, 10L, 19L, 39L)), row.names = c(NA, 6L), class = "data.frame")