R help - Jan 2010 - question about transpose

Hi all,

if I transpose a matrix with t(data), the newly created colums do not appear to
have the first row as header. How can I do to have all the newly created columns
have their first row as a header?

Thanks


Gabriele Zoppoli, MD
Ph.D. Fellow, Experimental and Clinical Oncology and Hematology, University of
Genova, Genova, Italy
Guest Researcher, LMP, NCI, NIH, Bethesda MD

Work: 301-451-8575
Mobile: 301-204-5642
Email: zoppolig at mail.nih.gov

On Jan 29, 2010, at 6:58 PM, Zoppoli, Gabriele (NIH/NCI) [G] wrote:
> Hi all,
>
> if I transpose a matrix with t(data), the newly created colums do  
> not appear to have the first row as header. How can I do to have all  
> the newly created columns have their first row as a header?
The term "header" doesn't really have meaning in R with reference
to
matrices. And the analog that might make sense, column names, fails to  
behave in the manner of your complaint.


 > M <- matrix(1:9, 3,3)
 > colnames(M) <- letters[1:3]
 > M
      a b c
[1,] 1 4 7
[2,] 2 5 8
[3,] 3 6 9
 > t(M)
   [,1] [,2] [,3]
a    1    2    3
b    4    5    6
c    7    8    9

So exactly _what_ is your problem?

-- 
David.

>
> Thanks
>
>
> Gabriele Zoppoli, MD
> Ph.D. Fellow, Experimental and Clinical Oncology and Hematology,  
> University of Genova, Genova, Italy
> Guest Researcher, LMP, NCI, NIH, Bethesda MD
>
> Work: 301-451-8575
> Mobile: 301-204-5642
> Email: zoppolig at mail.nih.gov
> ______________________________________________
> 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
Heritage Laboratories
West Hartford, CT

Hello,

Here are three examples.? I have a hunch you are looking for the last one.

> test <- matrix(LETTERS[1:6], nrow=2, dimnames=list(c("First",
"Second"))) #explicitly stating what the rownames are before
transposing
> test
?????? [,1] [,2] [,3]
First? "A"? "C"? "E"
Second "B"? "D"? "F"
> t(test)
???? First Second
[1,] "A"?? "B"
[2,] "C"?? "D"
[3,] "E"?? "F"

> test2 <- matrix(LETTERS[1:6], nrow=2)
> dimnames(test2) <- list(c(test2[,1])) # another option if you really
want the names to be whatever is in the first column
> test2
? [,1] [,2] [,3]
A "A"? "C"? "E"
B "B"? "D"? "F"
> t(test2)
???? A?? B
[1,] "A" "B"
[2,] "C" "D"
[3,] "E" "F"


## My guess is that you are looking for this one.  What was in the
first column in the original matrix, is removed from the transposed
matrix and used as the column names
## "[,-1]" indicates everything but column 1
## ncol has to be specified because I used matrix() so I could include dimnames
## dimnames are set to be the contents of the first column of the
original matrix
> test3 <- matrix(letters[1:6], nrow=2)
> test3
???? [,1] [,2] [,3]
[1,] "a"? "c"? "e"
[2,] "b"? "d"? "f"
> matrix(t(test3[,-1]), ncol=length(test3[,1]),
dimnames=list(NULL,c(test3[,1])))
???? a?? b
[1,] "c" "d"
[2,] "e" "f"


HTH,


Joshua



On Fri, Jan 29, 2010 at 3:58 PM, Zoppoli, Gabriele (NIH/NCI) [G]
<zoppolig at mail.nih.gov> wrote:
>
> Hi all,
>
> if I transpose a matrix with t(data), the newly created colums do not
appear to have the first row as header. How can I do to have all the newly
created columns have their first row as a header?
>
> Thanks
>
>
> Gabriele Zoppoli, MD
> Ph.D. Fellow, Experimental and Clinical Oncology and Hematology, University
of Genova, Genova, Italy
> Guest Researcher, LMP, NCI, NIH, Bethesda MD
>
> Work: 301-451-8575
> Mobile: 301-204-5642
> Email: zoppolig at mail.nih.gov
> ______________________________________________
> 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.


--
Joshua Wiley
Senior in Psychology
University of California, Riverside
http://www.joshuawiley.com/