[R] "flipping" vector and matrix

Rainer M Krug
Tue, 23 Oct 2007 14:34:17 -0000

Thanks Katharine

that answers my vector question.
The suggestion for the matrix is interesting and I would have never
thought about theat.

Thanks

Rainer

Katharine Mullen wrote:
> One way:
>
>> x<-1:9
>> rev(x)
> [1] 9 8 7 6 5 4 3 2 1
>
> for x as the matrix you gave:
>> x
>      [,1] [,2] [,3]
> [1,]    1    2    3
> [2,]    4    5    6
> [3,]    7    8    9
>>
>> apply(t(x),1,rev)
>      [,1] [,2] [,3]
> [1,]    7    8    9
> [2,]    4    5    6
> [3,]    1    2    3
>
>
> On Tue, 23 Oct 2007, Rainer M Krug wrote:
>
>> Hi
>>
>> I have a vector
>>
>> x <- c(1, 2, 3, 4, 5)
>>
>> and I want to "flip" it around, i.e. I need
>>
>> 5, 4, 3, 2, 1
>>
>> Is there a ssolution apart from
>>
>> y <- x[length(x):1]
>>
>>
>> I am also looking for the same for a matrix M, i.e.
>>
>> 1 2 3
>> 4 5 6
>> 7 8 9
>>
>> should become
>>
>> 7 8 9
>> 4 5 6
>> 1 2 3
>>
>> again, I am using
>>
>> M[1:dim(M)[1], dim(M)[2]:1]
>>
>>
>> Thanks
>>
>> Rainer
>>
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