[R] using nrow to identify one row

[Henrique Dallazuanna]

nrow is for number of rows in matrix/data.frame, here you can use:

NROW(temp[1,])
length(temp[1,])

But if you want the index of row try this:

unique(row(temp)[1,])

On 14/03/2008, Gregory Gentlemen <gregory_gentlemen at yahoo.ca> wrote:
> Hi fellow R-users,
>
>  I have run into a problem when trying to identify the number of rows in a matrix. Say we have an arbitrary 5 by 5 matrix called temp:
>
>  temp <- matrix(norm(25), nrow=5)
>
>  The problem is that nrow(temp[1,]) returns NULL. I would like it to return 1 because in my larger program I am indexing the rows of large matrices according to another variable and I need to test when the resulting matrices have 0, 1 or more rows.
>
>  Thanks in advance for any assistance.
>
>  Best regards,
>  Gregory Gentlemen
>
>
>
>
>  ---------------------------------
>
>         [[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.
>


-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O