R help - Jul 2009 - how to keep row name if there is only one row selected from a data frame

Hi, there:

Assume I have a dataframe with rownames like A with rownames like a to e,
> A
  [,1] [,2]
a    1    6
b    2    7
c    3    8
d    4    9
e    5   10

when I use A[1,], I lost the rowname for it, like below. How could I keep
it? Is there an easy way instead that I have to modify by myself after I
used A[1,] manually.
> A[1,]
[1] 1 6

Thanks,

W.



-- 
Weiwei Shi, Ph.D
Research Scientist
GeneGO, Inc.

"Did you always know?"
"No, I did not. But I believed..."
---Matrix III

	[[alternative HTML version deleted]]

Try A[1,,drop=FALSE] - see help("\[")

--- On Mon, 13/7/09, Weiwei Shi <helprhelp at gmail.com> wrote:
> From: Weiwei Shi <helprhelp at gmail.com>
> Subject: [R] how to keep row name if there is only one row selected from a
data frame
> To: "r-help at stat.math.ethz.ch" <R-help at
stat.math.ethz.ch>
> Received: Monday, 13 July, 2009, 1:55 PM
> Hi, there:
> 
> Assume I have a dataframe with rownames like A with
> rownames like a to e,
> 
> > A
> ? [,1] [,2]
> a? ? 1? ? 6
> b? ? 2? ? 7
> c? ? 3? ? 8
> d? ? 4? ? 9
> e? ? 5???10
> 
> when I use A[1,], I lost the rowname for it, like below.
> How could I keep
> it? Is there an easy way instead that I have to modify by
> myself after I
> used A[1,] manually.
> 
> > A[1,]
> [1] 1 6
> 
> Thanks,
> 
> W.
> 
> 
> 
> -- 
> Weiwei Shi, Ph.D
> Research Scientist
> GeneGO, Inc.
> 
> "Did you always know?"
> "No, I did not. But I believed..."
> ---Matrix III
> 
> ??? [[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.
>

On Mon, Jul 13, 2009 at 5:55 AM, Weiwei Shi<helprhelp at gmail.com>
wrote:
> Hi, there:
>
> Assume I have a dataframe with rownames like A with rownames like a to e,
>
>> A
> ?[,1] [,2]
> a ? ?1 ? ?6
> b ? ?2 ? ?7
> c ? ?3 ? ?8
> d ? ?4 ? ?9
> e ? ?5 ? 10
>
> when I use A[1,], I lost the rowname for it, like below. How could I keep
> it? Is there an easy way instead that I have to modify by myself after I
> used A[1,] manually.
>
>> A[1,]
> [1] 1 6
I think if you do str(A) you'll discover it's a matrix, not a data
frame.

Hadley

-- 
http://had.co.nz/