[R] Switch two rows in a matrix

[Birgitle]

You could perhaps do it like that

a<-a[c(1,2,4,3),]

B.


Zhang Yanwei - Princeton-MRAm wrote:
> 
> Hi all,
>   I have a 4 by 4 matrix, and I want to switch row 2 and row 3 first, then
> switch column 2 and column 3. Is there an easy way to do it?
> The following is a tedious way to get what I want. But I wonder if there
> is a way to simplify this.
> 
>  > a=matrix(rnorm(16),4,4)
>> a
>             [,1]       [,2]        [,3]       [,4]
> [1,]  0.33833811 -0.9422273 -0.06181611 -1.8346134
> [2,] -0.68167996  0.2004836  0.71079887 -1.1590184
> [3,]  0.07811688  0.1338694 -1.61262688  0.2988365
> [4,]  0.21869786 -1.6356661 -0.13694344 -1.2121355
>> b=a
>> b[2,]=a[3,]
>> b[3,]=a[2,]
>> b
>             [,1]       [,2]        [,3]       [,4]
> [1,]  0.33833811 -0.9422273 -0.06181611 -1.8346134
> [2,]  0.07811688  0.1338694 -1.61262688  0.2988365
> [3,] -0.68167996  0.2004836  0.71079887 -1.1590184
> [4,]  0.21869786 -1.6356661 -0.13694344 -1.2121355
>> c=b
>> c[,2]=b[,3]
>> c[,3]=b[,2]
>> c
>             [,1]        [,2]       [,3]       [,4]
> [1,]  0.33833811 -0.06181611 -0.9422273 -1.8346134
> [2,]  0.07811688 -1.61262688  0.1338694  0.2988365
> [3,] -0.68167996  0.71079887  0.2004836 -1.1590184
> [4,]  0.21869786 -0.13694344 -1.6356661 -1.2121355
> 
> 
> Sincerely,
> Yanwei Zhang
> Department of Actuarial Research and Modeling
> Munich Re America
> Tel: 609-275-2176
> Email: yzhang at munichreamerica.com<mailto:yzhang at munichreamerica.com>
> 
> 
> 	[[alternative HTML version deleted]]
> 
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> 
> 


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