4

I am trying to read a network data (graph of ids) in R. The file is named 'network.txt' and data is as follows:

4 0
5 0
6 0
7 0
8 0
9 0
4029 1
4030 1
4031 1
4032 1
4033 1
19088 9040
19089 9040
19090 9040
19091 9040
19092 9040
19093 9040
19094 9040
19095 9040
19096 9040
19097 9040

And, I am reading it using read.table() module.

data = read.table("network.txt",sep="\t",header=FALSE)
colnames( data ) <- unlist(c('to', 'from'))

Error in `colnames<-`(`*tmp*`, value = c("to", "from")) : 
  'names' attribute [2] must be the same length as the vector [1]

So, how to assign column names? Is there any mistake reading the original data file ?

Sijan Bhandari
  • 2,941
  • 3
  • 23
  • 36
  • 1
    Given the error, I suspect your data is not read in correctly. Check `str(data)`. Most likely you just need to take out the `sep` parameter, and it will work. – alistaire Aug 02 '16 at 02:56
  • @ProcrastinatusMaximus I would read the question and answer before dupe tagging. I think the linked post nowhere addresses the issue in the question unless you found it somewhere hidden in the link. – akrun Aug 02 '16 at 06:48

2 Answers2

5

You can either provide the column names within the read.table function call, as such:

read.table("network.txt", col.names = c("Col1", "Col2"))

Or, you can also do it in a similar fashion to your attempt with the names function:

test1 <- read.table("Question1.txt")
names(test1) <- c("col1", "col2")
David A. Heisler
  • 69
  • 4
2

We just need 

colnames( data ) <- c('to', 'from')

as c('to', 'from') returns a vector and unlist does nothing here. The unlist is used in cases where the output is list or (data.frame which is also a list with elements of equal length aka columns)

Regarding the error, it is possible that we used the wrong sep resulting in a single column which can be identified by checking the str(data). I would use sep=""

In addition to the above recommendation, we can specify the col.names in read.table

data <- read.table("network.txt",sep="",header=FALSE, col.names = c("to", "from"))

Or use fread from data.table (which picks up the delimiter automatically)

library(data.table)
data <- fread("network.txt", header=FALSE, col.names = c("to", "from"))
akrun
  • 874,273
  • 37
  • 540
  • 662
  • 1
    Thank you @akrun, I am a beginner in R. And, I thought playing with real data is a good idea to start with it. It works very well now. – Sijan Bhandari Aug 02 '16 at 03:00