# [R] convert a data frame to matrix - changed column name

Robin Hankin r.hankin at noc.soton.ac.uk
Thu Apr 6 16:22:47 CEST 2006

```Hi

set the column names to NULL:

> a <- data.frame(x=1:4,y=4:1)
> aa <- as.matrix(a)
> colnames(aa) <- NULL
> aa
[,1] [,2]
1    1    4
2    2    3
3    3    2
4    4    1

best wishes

Robin

On 6 Apr 2006, at 15:16, Muhammad Subianto wrote:

> I have a question, which very easy to solve, but I can't find a
> solution.
> I want to convert a data frame to matrix. Here my toy example:
>
>> L3 <- c(1:3)
>> L10 <- c(1:6)
>> d <- data.frame(cbind(x=c(10,20), y=L10), fac=sample(L3, + 6,
>> repl=TRUE))
>> d
>    x y fac
> 1 10 1   1
> 2 20 2   1
> 3 10 3   1
> 4 20 4   3
> 5 10 5   2
> 6 20 6   2
>> is.data.frame(d)
> [1] TRUE
>> sapply(d, function(x) unlist(x, use.names=FALSE))
>       x y fac
> [1,] 10 1   1
> [2,] 20 2   1
> [3,] 10 3   1
> [4,] 20 4   3
> [5,] 10 5   2
> [6,] 20 6   2
>> is.matrix(sapply(d, function(x) unlist(x, use.names=FALSE)))
> [1] TRUE
>>
>
> Yes, I get a matrix TRUE. But I need to change a column name like [,1]
> [,2] [,3]. I need the result like
>
>      [,1] [,2] [,3]
> [1,]   10    1    1
> [2,]   20    2    1
> [3,]   10    3    1
> [4,]   20    4    3
> [5,]   10    5    2
> [6,]   20    6    2
>
> How can I do that?
>
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> guide.html

--
Robin Hankin
Uncertainty Analyst
National Oceanography Centre, Southampton
European Way, Southampton SO14 3ZH, UK
tel  023-8059-7743

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