[R] How to find the index
Duncan Murdoch
murdoch at stats.uwo.ca
Tue Sep 16 17:16:16 CEST 2008
On 9/16/2008 11:04 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 .
You can't. Sorting loses information, and the original index is part of
the information that is lost.
What you should do is use order() instead of sort(). x[order(x)] is the
same as sort(x), but no information is lost.
Duncan Murdoch
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