在具有复杂数据的 R 中使用 igraph 创建图形

Question

I want to create a graph from a data frame with multiple data columns, where all of the columns contain vertices, like this: example data

If two vertices are found in a row together, then they should be connected in the graph. In my example, vertex "Case no. 3" should be connected to the following vertices: "case no. 1", "Jon", "case no. 5", "Bill" (NA should be ignored). Thanks in advance!

Answer 1

Your question is about manipulate the raw data, 'cause you need to construct your edgelist correctly. The only way to do this is to indicate two columns, with the sender of the link (col. 1), and the receiver of the link (col. 2). Self-directed links are allowed (eg, from 'a' to 'a'). The others columns are caracteristics of the links, ever.

Your example edgelist show 3 columns of vertices: this is not a valid edgeslist, one of the columns is useless. So,

1. you'll have to construct a valid edgelist, by manipulate the data (see below).

2. Then, you should tell igraph what is your edgelist and construct a graph, like in this answer and/or this one (sorry for the shameless auto-promote).

In order to construct a valid edgelist from the example you provide, with tidyverse tools and the %>% operator:

    # ↓ SAMPLE DATA (colnames are different from the ones you provided) ↓
    
  raw_data <- data.frame(case_no=c(1, 2,3, 4), 
                        related_case =c(3,5,5, NA) ,
                        received_by = c("Jon", "Wendy","Jon", NA) , 
                        packed_by = c(NA, "Wendy", "Bill", NA) ) 

# ↓ First series of links ↓
edges_list <- raw_data %>% 
select(FROM = case_no, related_case, TO = received_by) %>% 
mutate(TYPE = 'Received') # ↑ THIS IS ONLY THE FIRST COLUMNS OF RECEIVERS
  
 # ↓ APPEND THE SECOND LIST OF RECEIVER TO THE FIRST VERSION OF THE EDGESLIST↓ 

 edges_list <- select(raw_data, FROM = case_no, related_case, TO = packed_by) %>% 
 mutate(TYPE = 'Packed') %>% #↑ HERE THE SECOND COLUMN OF RECEIVERS↑
   rbind(edges_list)   

edges_list <- na.omit(edges_list) # ← REMOVE NA FILLED ROWS

edges_list %>% igraph::graph_from_data_frame(directed = T) %>% 
  
  igraph::plot.igraph() # CREATE YOUR GRAPH