?order
cheers,
Rolf Turner
On 03/11/2013 02:24 PM, Jie wrote:
Dear All,
Suppose I have a vector X = (x_1, x_2, ...., x_n), X_sort = sort(X)
= (x_(1), x_(2), ... , x(n) ),
and I would like to know the original position of these ordered x_(i)
in X, how can I do it?
case 1: all values are unique
x <- c( 3, 5, 4, 6)
x.sort <- sort(x) #
# I would like to obtain a vector (1, 3, 2, 4) which indicates that 3
in x is still the 1st element in x.sort, 5 is at the 3rd position in
x.sort. etc.
case 2: some x_i's have the same value
x <- c(3, 3, 5, 5, 4, 4, 6, 6)
I would like to obtain a vector as (1, 2, 5, 6, 3, 4, 7, 8)
I do not want to use which and loop over the vector to do it since for
a long vector it is not fast enough.
Thank you for your suggestion.
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