# [R] matrix transpose

Daniel Viar dan.viar at gmail.com
Sun Feb 15 21:29:30 CET 2009

```Here's one way that seems to work:

a <- matrix(1:30,5,6)
# Create a target for the transpose
b <- matrix(1:(nrow(a)*ncol(a)),ncol(a),nrow(a))
# populate b with the transpose of a
for (i in 1:ncol(a)) { b[i,1:(nrow(a))] <- a[1:(nrow(a)),i]}
# Check:  Did it work?
all.equal(b,t(a))

I'm sure there's a more "R-like" way of doing this...

Cheers,
Dan Viar
Chesapeake, VA

On Sun, Feb 15, 2009 at 3:05 PM, Rolf Turner <r.turner at auckland.ac.nz> wrote:
>
> On 16/02/2009, at 8:36 AM, Roger wrote:
>
>> This is supposed to be an easy operation, but R 2.8.1 on Mac OS X gives me
>> a
>> lot trouble. the t() function simply does not work properly.  What I mean
>> is
>> it works sometimes but does not work at the most of the time, even with
>> the
>> same matrix.
>>
>> this is an example taken from R help
>>
>>> a <- matrix(1:30, 5,6)
>>> t(a)
>>
>> Error in t(a) : unused argument(s) (1:30)
>>
>> It just gives this error.  If I restart my Mac (Yeah, have to restart the
>> OS), then there are chances t() works, but sometimes it still does not
>> work.
>>
>> Can anyone give me another way to compute the transpose in R?
>
> No.  That's the only way. :-)
>
> (1) I have no problem doing your example (on Mac OS X).
>
> (2) The error is weird in that you passed the argument ``1:30'' to matrix()
>    not to t().  Something is corrupted in your system.  What happens when
>    you just type ``a'' (rather than t(a)) after creating a?  What happens
>    when you type ``t'' (no parentheses) and ``matrix'' (no parentheses)?
>
> (3) Possibly you have a workspace that is corrupted in some way.  Try
> starting
>    R with the --no-restore-data flag and see what happens.  Or move .RData
>    to (say) ``save.RData'' before you start R, and see what happens.
>
> (4) Good luck!
>
>        cheers,
>
>                Rolf Turner
>
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