R: select by color and by ID
问题 I have the following data in R Data_I_Have <- data.frame( "Node_A" = c("John", "John", "John", "Peter", "Peter", "Peter", "Tim", "Kevin", "Adam", "Adam", "Xavier"), "Node_B" = c("Claude", "Peter", "Tim", "Tim", "Claude", "Henry", "Kevin", "Claude", "Tim", "Henry", "Claude"), " Place_Where_They_Met" = c("Chicago", "Boston", "Seattle", "Boston", "Paris", "Paris", "Chicago", "London", "Chicago", "London", "Paris"), "Years_They_Have_Known_Each_Other" = c("10", "10", "1", "5", "2", "8", "7", "10",