[R] Array dimnames

[Domenico Vistocco]

dave mitchell wrote:
> Dear all,
> Possibly a rudimentary question, however any help is greatly appreciated.  I
> am sorting a large matrix into an array of dim(p(i),q,3).  I put each entry
> into a corresponding matrix (1 of the 3) based on some criteria.  I figure
> this will assist me in condensing code as I can loop through the 3rd
> dimension of the array instead of generating 3 separate matrices and using
> the same block of code 3 times.  My question is how to get the colnames of
> the 3 nested matrices in the array to match the colnames of the data
> matrix.  In other words...
>   
Denoting with array3d the array and with matrix2d the data matrix:

colnames(array3d)=colnames(array3d)

Otherwise, using dimnames:
dimnames(array3d)=list(NULL,colnames(array3d),NULL)

You can operate using the "[" operator, that is:
array3d[,"region",] to extract the region columns from each dimension.

You obtain the same effect using the column number, i.e.
array3d[,2,]

domenico
> DATA:
>    Exp   region   Qty   Ct  ...q
> 1   S      CB     3.55  2.15  .
> 2   S      TG     4.16  2.18  .
> 3   C      OO     2.36  3.65  .
> 4   C   .           .         .
> .   .     .           .       .
> .   .       .           .     .
> .   .         .           .   .
> p   ...........................
>
>
>
> ARRAY
> 1
>    [,1]   [,2]    [,3] [,4]...q
> 1   SOME DATA WILL FILL THIS   .
> 2   .  .              .        .
> 3   .   .              .       .
> 4   .    .              .      .
> .   .     .              .     .
> .   .      .              .    .
> .   .       .              .   .
> P(1) ...........................
>
> 2
>    [,1]   [,2]    [,3] [,4]...q
> 1   SOME DATA WILL FILL THIS   .
> 2   .  .              .        .
> 3   .   .              .       .
> 4   .    .              .      .
> .   .     .              .     .
> .   .      .              .    .
> .   .       .              .   .
> P(2) ...........................
> 3
>    [,1]   [,2]    [,3] [,4]...q
> 1   SOME DATA WILL FILL THIS   .
> 2   .  .              .        .
> 3   .   .              .       .
> 4   .    .              .      .
> .   .     .              .     .
> .   .      .              .    .
> .   .       .              .   .
> P(3) ...........................
>
> Again, how to get those [,1], [,2]... to read (and operate) in the same
> fashion as the column names in the data matrix?  Also, am I interpreting the
> dimensions of the array incorrectly?  Please feel free to post any helpful
> links on the subject, as I have found "dimnames" and "array" in the R-help
> documentation unhelpful.  Any help is greatly appreciated.
>
> Dave Mitchell
> Undergraduate: Statistics and Mathematics,
> University of Illinois, Urbana-Champaign
>
> 	[[alternative HTML version deleted]]
>
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