[R] how to create column names for the matrix

[lily li]

If replace 1:5 to char2 = c('east','west','south','north','central'), how
to put on column names with the original structure? Thanks again.


On Wed, Jul 27, 2016 at 12:40 PM, Hervé Pagès <hpages at fredhutch.org> wrote:

> Hi,
>
>
> On 07/27/2016 11:17 AM, lily li wrote:
>
>> Hi all,
>>
>> I want to ask that how to create column names for a matrix. For example,
>> the matrix below, the column names should be: 1-A, 1-B, 1-C, 1-D, 2-A,
>> 2-B,
>> 2-C, 2-D, 3-A, etc. Thanks for your help.
>>
>> chars = c('A','B','C','D')
>> matrix1 = matrix(nrow = length(1:100), ncol = length(1:5)*length(chars))
>> k = 0
>> for(i in seq(1:length(1:5))){
>>   for(j in seq(1:length(chars))){
>>     k = k+1
>>     matrix1[,k] = c(1:100)[k]
>>   }
>> }
>>
>
> Also how could you possibly use such level of code obfuscation to
> perform such simple initialization of your matrix?
>
> My 1st advice would be that you slow down and take the time to compare
> seq(1:length(1:5)) with 1:length(1:5) with 1:5. It will be a great
> learning experience!
>
> As for initializing your matrix, what about doing
>
>   ncol <- 5 * length(chars)
>   matrix1 <- matrix(seq_len(ncol), nrow=100, ncol=ncol, byrow=TRUE)
>
> instead?
>
> Then set the colnames with:
>
>   colnames(matrix1) <- paste(rep(1:5, length(chars)), chars, sep="-")
>
> Cheers,
> H.
>
>
>>         [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> 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.
>>
>>
> --
> Hervé Pagès
>
> Program in Computational Biology
> Division of Public Health Sciences
> Fred Hutchinson Cancer Research Center
> 1100 Fairview Ave. N, M1-B514
> P.O. Box 19024
> Seattle, WA 98109-1024
>
> E-mail: hpages at fredhutch.org
> Phone:  (206) 667-5791
> Fax:    (206) 667-1319
>

	[[alternative HTML version deleted]]