[R] Convert 2-dim array to 3-dim array

[David Winsemius]

On Jun 4, 2012, at 12:54 PM, arun wrote:

> Hi Dave,
>
> I tested the "as.array".  It gives a different dimension when  
> compared to "array"

Interesting. `as.array basically throws away a 'dim' argument and  
substitutes length(x). Thanks for the correction.

-- 
David.
>
> set.seed(1)
> datE<-data.frame(A=rnorm(30,0.5))
> myArr=as.array(unlist(datE),dim=c(5,2,3))
>> myArr
>          A1          A2          A3          A4          A5           
> A6
> -0.12645381  0.68364332 -0.33562861  2.09528080  0.82950777  
> -0.32046838
>          A7          A8          A9         A10         A11          
> A12
>  0.98742905  1.23832471  1.07578135  0.19461161  2.01178117   
> 0.88984324
>         A13         A14         A15         A16         A17          
> A18
> -0.12124058 -1.71469989  1.62493092  0.45506639  0.48380974   
> 1.44383621
>         A19         A20         A21         A22         A23          
> A24
>  1.32122120  1.09390132  1.41897737  1.28213630  0.57456498  
> -1.48935170
>         A25         A26         A27         A28         A29          
> A30
>  1.11982575  0.44387126  0.34420449 -0.97075238  0.02184994   
> 0.91794156
>> is.array(myArr)
> [1] TRUE
>> dim(myArr)
> [1] 30
>
>
>> myArr1=array(unlist(datE),dim=c(5,2,3))
>> myArr1
> , , 1
>
>            [,1]       [,2]
> [1,] -0.1264538 -0.3204684
> [2,]  0.6836433  0.9874291
> [3,] -0.3356286  1.2383247
> [4,]  2.0952808  1.0757814
> [5,]  0.8295078  0.1946116
>
> , , 2
>
>            [,1]      [,2]
> [1,]  2.0117812 0.4550664
> [2,]  0.8898432 0.4838097
> [3,] -0.1212406 1.4438362
> [4,] -1.7146999 1.3212212
> [5,]  1.6249309 1.0939013
>
> , , 3
>
>           [,1]        [,2]
> [1,]  1.418977  0.44387126
> [2,]  1.282136  0.34420449
> [3,]  0.574565 -0.97075238
> [4,] -1.489352  0.02184994
> [5,]  1.119826  0.91794156
>
>> dim(myArr1)
> [1] 5 2 3
>
>
> A.K.
>
>
>
>
> ----- Original Message -----
> From: David Winsemius <dwinsemius at comcast.net>
> To: David Zastrau <davidz at tzi.de>
> Cc: r-help at r-project.org
> Sent: Monday, June 4, 2012 10:45 AM
> Subject: Re: [R] Convert 2-dim array to 3-dim array
>
>
> On Jun 4, 2012, at 5:08 AM, David Zastrau wrote:
>
>> Hello R-users,
>>
>> I'd like to load data from a CSV-file to a 3-dimensional array.  
>> However
>> the default seems to be 2-dimensional.
>
> No.  that is not the problem.
>> It would also be ok to load the
>> data and then convert it to a 3-dimensional structure.
>>
>> I've been trying:
>>
>>    dat = read.csv(filename)
>>    myArr = as.array(dat, dim = c(12,100,3))
>>
>> However, I get an error message:
>>
>> Error in `dimnames<-.data.frame`(`*tmp*`, value = list(n)) :
>> invalid 'dimnames' given for data frame
>
> A dataframe is a list structure while both array and matrix are  
> expecting the first argument to be an atomic vector. Try this  
> (although it is a blind guess because you have not provided the  
> structure of 'dat'
>
> myArr = as.array( unlist(dat), dim = c(12,100,3))
>
> --David.
>
>>
>>
>> And I don't know how how to set the dimnames.
>>
>> I would appreciate any help!
>>
>> Best Wishes
>> Dave
>>
>>     [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>
> David Winsemius, MD
> West Hartford, CT
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

David Winsemius, MD
West Hartford, CT