r - How do you build a graph from a data frame using the igraph package?

Question

Any way to build a graph ( igraph package ) from a Data Frame in R ?

The data frame contains node relationships.

    df = data.frame ( 
A = c("Berlin", "Amsterdam", "New York") , 
B = c("Munich", "Utrecht", "Chicago") 
) 

Edges are :

Berlin -> Munich
Amsteram -> Utrecht
New York -> Chicago

Answer 1

igraph is very flexible and I'm sure there are a number ways to accomplish this. I found the tutorials provided on the website to be very helpful.

Here's one simple way to create a network plot from a data.frame:

library(igraph)

df <- data.frame(
  A = c("Berlin", "Amsterdam", "New York") , 
  B = c("Munich", "Utrecht", "Chicago"))

df.g <- graph.data.frame(d = df, directed = FALSE)

plot(df.g, vertex.label = V(df.g)$name)

Note: For current versions of igraph (as of Version 1.2.1), the graph.data.frame() function is changed to graph_from_data_frame(), which is the only function out of these two to appear in the documentation. The graph.data.frame() function will still work, though.