How to find the index

 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.

HTH

  regards
-----------------------------------------------
Peng Jiang ?? ,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