How to write and read matrix from file without column names?

Question

A matrix Aexample is:

Aexample
[,1] [,2] [,3] [,4]
[1,]  0.6  0.4 0.00  0.0
[2,]  0.4  0.4 0.00  0.0
[3,]  0.4  0.4 0.00  0.0
[4,]  0.0  0.0 0.40  0.4
[5,]  0.0  0.0 0.34  0.4
[6,]  0.0  0.0 0.40  0.4

It is saved to a file by

write.table (Aexample, file = "~/R/Aexample", row.names = FALSE, col.names = FALSE);

And then I read by

Aexample = as.matrix(read.table(file="~/R/Aexample"));

But the result always has V1 V2 V3 V4 column names that I don't want:

    V1  V2   V3  V4
[1,]  0.6  0.4 0.00  0.0
[2,]  0.4  0.4 0.00  0.0
[3,]  0.4  0.4 0.00  0.0
[4,]  0.0  0.0 0.40  0.4
[5,]  0.0  0.0 0.34  0.4
[6,]  0.0  0.0 0.40  0.4

What's the simplest way to save the Aexample matrix and then read from file and get the original Aexample matrix? (Not to read to aa = as.matrix(read.table(file="~/R/Aexample")) and then create Aexample from aa with many lines of code)

This will probably get moved to SO, but you can just write.table with col.names = TRUE and then read it in with header = T. This will preserve your [,1], [,2] headers. — Chris C

Cath Cath · Accepted Answer · 2014-11-28T07:56:20

You can do that in two steps :

1.

Aexample = as.matrix(read.table(file="~/R/Aexample"))

2.

colnames(Aexample) <- NULL

Example

aaa<-matrix(1:24,nrow=6)

> aaa
     [,1] [,2] [,3] [,4]
[1,]    1    7   13   19
[2,]    2    8   14   20
[3,]    3    9   15   21
[4,]    4   10   16   22
[5,]    5   11   17   23
[6,]    6   12   18   24

write.table(aaa,"aaa.txt",col.names=F,row.names=F)

bbb<-as.matrix(read.table(file="aaa.txt",header=T))
colnames(bbb)<-NULL

> bbb
     [,1] [,2] [,3] [,4]
[1,]    1    7   13   19
[2,]    2    8   14   20
[3,]    3    9   15   21
[4,]    4   10   16   22
[5,]    5   11   17   23
[6,]    6   12   18   24

How to write and read matrix from file without column names?

1 Answers