[R] array to matrix or data.frame

Daniel Malter
Sun, 27 Sep 2009 23:24:25 -0000

Works a charme; thanks much everybody. Daniel.


David Winsemius wrote:
>
>
> On Sep 27, 2009, at 6:33 PM, Daniel Malter wrote:
>
>>
>> Hi, I have an array of dimension 6:6:160000. I want to stack the
>> 160000
>> slices of the array into a matrix or a data frame of dimension
>> 6:(6*160000=960000) in order to write it to a csv file. It seems I
>> cannot
>> get the matrix or data.frame functions to put the values from the
>> array in
>> the same order as they appear in the array easily, but I am almost
>> sure
>> there is an easy way to do this.
>>
>> #Here is code for a small 6:6:2 array.
>>
>> x=rep(rep(1:6,each=6),2)
>> dim(x)=c(6,6,2)
>>
>> x
>>
>> #Matrix approach 1:
>>
>> matrix(x,nrow=12,ncol=6,byrow=F)
>>
>> #Matrix approach 2:
>>
>> matrix(x,nrow=12,ncol=6,byrow=T)
>>
>> #Data frame approach (cbinds rather than rbinds):
>>
>> data.frame(x)
>>
>> None of the above works as I would like to. The "correct"
approach
>> should
>> stack the same values all in the same column of the matrix or data
>> frame. I
>> also could not get "stack" to work correctly and would
appreciate
>> your help.
>
> apply(x, 2 , I)
>        [,1] [,2] [,3] [,4] [,5] [,6]
>   [1,]    1    2    3    4    5    6
>   [2,]    1    2    3    4    5    6
>   [3,]    1    2    3    4    5    6
>   [4,]    1    2    3    4    5    6
>   [5,]    1    2    3    4    5    6
>   [6,]    1    2    3    4    5    6
>   [7,]    1    2    3    4    5    6
>   [8,]    1    2    3    4    5    6
>   [9,]    1    2    3    4    5    6
> [10,]    1    2    3    4    5    6
> [11,]    1    2    3    4    5    6
> [12,]    1    2    3    4    5    6
>
> --
>
> David Winsemius, MD
> Heritage Laboratories
> West Hartford, CT
>
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>
>

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