[R] ordering

[Peter Alspach]

Kia ora Aaron

As you have identified, test[,2] is not numeric - it is probably factor.
Your function must have made the conversion, so you may want to modify
that.  Alternative, try:

test[order(as.numeric(as.character(test[,2]))),] 

BTW, str(test) is a good way to find out more about the structure of
your object.

HTH ....

Peter Alspach




> -----Original Message-----
> From: r-help-bounces at r-project.org 
> [mailto:r-help-bounces at r-project.org] On Behalf Of aaron wells
> Sent: Wednesday, 11 March 2009 8:30 a.m.
> To: r-help at r-project.org
> Subject: [R] ordering
> 
> 
> Hello, I would like to order a matrix by a specific column. 
> For instance:
> 
>  
> 
> > test
>       [,1] [,2] [,3]
>  [1,]    1  100   21
>  [2,]    2    3   22
>  [3,]    3  100   23
>  [4,]    4   60   24
>  [5,]    5   55   25
>  [6,]    6   45   26
>  [7,]    7   75   27
>  [8,]    8   12   28
>  [9,]    9   10   29
> [10,]   10   22   30
> >
> 
>  test[order(test[,2]),]
>       [,1] [,2] [,3]
>  [1,]    2    3   22
>  [2,]    9   10   29
>  [3,]    8   12   28
>  [4,]   10   22   30
>  [5,]    6   45   26
>  [6,]    5   55   25
>  [7,]    4   60   24
>  [8,]    7   75   27
>  [9,]    1  100   21
> [10,]    3  100   23
> 
> 
> This works well and good in the above example matrix.  
> However in the matrix that I actually want to sort (derived 
> from a function that I wrote) I get something like this:
> 
>  
> 
> > test[order(as.numeric(test[,2])),]     ### First column is row.names
> 
> 
>          f con f.1 cov f.2 minimum f.3 maximum f.4   cl
> asahi    * 100   *   1   *     0.1   *       2   * test
> castet   * 100   *   2   *     0.1   *       5   * test
> clado    * 100   *   1   *     0.7   *       2   * test
> aulac    *  33   *   0   *     0.1   *     0.1   * test
> buell    *  33   *   0   *     0.1   *     0.1   * test
> camlas   *  33   *   0   *     0.1   *     0.1   * test
> carbig   *  33   *   1   *       1   *       1   * test
> poaarc   *  67   *   0   *     0.1   *     0.1   * test
> polviv   *  67   *   0   *     0.1   *     0.1   * test
> 
> 
>  
> 
> where R interprets 100 to be the lowest value and orders 
> increasing from there.  
> 
>  
> 
> > is.numeric(test[,2])
> [1] FALSE
> > is.double(test[,2])
> [1] FALSE
> > is.integer(test[,2])
> [1] FALSE
> > is.real(test[,2])
> [1] FALSE
> 
> 
>  
> 
> My questions are:  Why is this happening? and How do I fix  it? 
> 
>  
> 
> Thanks in advance!
> 
>  
> 
>                               Aaron Wells
> 
> _________________________________________________________________
> 
> 
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