# [R] A matrix calculation

David Winsemius dwinsemius at comcast.net
Sun Aug 23 21:08:02 CEST 2009

```On Aug 23, 2009, at 2:53 PM, Bogaso wrote:

>
> No no, I actually want following result :
>
> 7,   14,   21, 6,   13,   20, 5,   12,   19,............

Ooops. That is what I thought you wanted, but I didn't check very
carefully, did I?

c(apply(mat[7:1,],1,I) )

# the I() function just returns "itself" and gets supplied a row at a
time.

[1]  7 14 21  6 13 20  5 12 19  4 11 18  3 10 17  2  9 16  1  8 15
>
>
>
>
>
> David Winsemius wrote:
>>
>>
>> On Aug 23, 2009, at 2:37 PM, Bogaso wrote:
>>
>>>
>>> I have suppose a matrix like that
>>>
>>>> mat <- matrix(1:21, 7)
>>>> mat
>>>    [,1] [,2] [,3]
>>> [1,]    1    8   15
>>> [2,]    2    9   16
>>> [3,]    3   10   17
>>> [4,]    4   11   18
>>> [5,]    5   12   19
>>> [6,]    6   13   20
>>> [7,]    7   14   21
>>>
>>>> From this matrix, I want to create a vector like tha :
>>>
>>> c(mat[7,], mat[6,], mat[5,], ....., mat[1,])
>>>
>>> Can anyone please guide me, how to do that?
>>
>>  c( mat[7:1,] )
>>
>> # [1]  7  6  5  4  3  2  1 14 13 12 11 10  9  8 21 20 19 18 17 16 15
>>
>> --
>>
>> David Winsemius, MD
>> Heritage Laboratories
>> West Hartford, CT
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>>
>
> --
> View this message in context: http://www.nabble.com/A-matrix-calculation-tp25106048p25106224.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help