CODEWITHSUNDEEP
pythonrgraphnetwork-programmingigraph
Noah16
Noah16

Reputation: 294

import an undirected graph in R from text file

The output I have trouble reading an undirected graph in R, I've tried to import it to R from a text file "graph.txt" which contains a large number of edges (about 1000) but the problem:

R is not reading the whole graph from the text file and it is omitting a large number of the edges I followed the steps I have found in tutorials for R and the related previous questions in this website but I couldn't modify it.

The graph.txt looks like:

383 886 
777 915 
793 335 
386 492 
649 421 
362 27 
690 59 
763 926 
540 426 
172 736 
211 368 
567 429 
782 530

and the functions I used:

library("igraph")
dd<-scan("graph.txt")
gg<-read_graph("graph.txt",directed=FALSE)
gg

the result looks like: 

... 763-- 785 326-- 984 946-- 946 326--1103 326-- 592 698--1636 326--1807
+ ... omitted several edges

Any help please to let R import the whole number of edges from the txt file

Thanks in advance

P.S: I am trying to import data as a graph only (not a table or matrix) to calculate the diameter for the graph using the function:

diameter(graph, directed = FALSE, weights = NULL)

Upvotes: 1

Views: 1033

Answers (1)

Niklas Braun
Niklas Braun

Reputation: 413

What I usually do is import the file first, then convert it to a graph to be safe. So 

library(igraph)
f <- read.table(file = "graph.txt")
edges <- c()
for (e in 1:dim(f)[1]){
  edges <- append(edges, c(f[e, 1], f[e, 2]))
}
g <- graph(edges, directed = FALSE)
g
#IGRAPH U--- 926 13 -- 
#+ edges:
#[1] 383--886 777--915 335--793 386--492 421--649  27--362  59--690 763--926 426--540 172--736
#[11] 211--368 429--567 530--782

Upvotes: 2

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