[R] How to find the index

Don McKenzie dmck at u.washington.edu
Tue Sep 16 19:22:17 CEST 2008

On 16-Sep-08, at 8:04 AM, Peng Jiang wrote:

>  Dear R experts,
>   i have a vector z , i have to do something after z is sorted. how  
> can i find the original index, i.e., before sorting, of a certain  
> element in the sorted vector  .
>  thanks in advance

I use this function provided in the old "Blue Book".

sort.mat <-
function(mat1, col1)
	mat1[sort.list(mat1[, col1]),  ]

where "mat1" is the matrix to be sorted (in your case a n x 2 matrix  
of your vector and an index vector), and
"col1" is the column to be sorted on.


>   regards
> -----------------------------------------------
> Peng Jiang 江鹏 ,Ph.D. Candidate

Don McKenzie, Research Ecologist
Pacific WIldland Fire Sciences Lab
US Forest Service

Affiliate Professor
College of Forest Resources
CSES Climate Impacts Group
University of Washington

desk: 206-732-7824
cell: 206-321-5966
dmck at u.washington.edu
donaldmckenzie at fs.fed.us

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