[R] lexicographic sort of ordered lists
Spencer Graves
spencer.graves at pdf.com
Fri Jul 18 22:30:15 CEST 2003
"?order"?
J. P. Morgan wrote:
> Does anyone know how to execute the following sort problem in R? Matrix X
> has positive integer entries, and each column has been sorted in ascending
> order. The problem is now to order the columns lexicographically. For
> instance if the matrix X is
>
>
>
> 1 2 1 1 2
>
> 2 2 3 3 2
>
> 3 5 5 4 2
>
>
>
> then the result should be
>
>
>
> 1 1 1 2 2
>
> 2 3 3 2 2
>
> 3 4 5 2 5
>
>
>
> Let ONE be a vector of 1's of length ncol(X). The result in this example can
> be accomplished by
>
>
>
> X=X[,order(ONE,X[1,],X[,2],X[,3])]
>
>
>
> but I need a method that will work regardless of k=number of rows of X. That
> is, the program must be able to accept any integer-valued matrix X for which
> each column is sorted, then permute columns accordingly.
>
>
>
> Thanks, JP
>
>
>
>
>
>
> [[alternative HTML version deleted]]
>
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