[R] Q: sort a matrix by picking up columns?

[Yuyun Jessie Yang]

Hi,

I am wondering how to write a function which sorts a matrix by giving a
vector of column numbers.

Suppose we have a matrix (or data frame) "Mat" and I want to obtain
order(Mat[,1], Mat[,3], Mat[,6,], Mat[,8], Mat[,10], Mat[,13])
in order to sort the matrix by those columns. Is there a way to write a
function so that I can give a vector of the column numbers 
c(1,3,6,8,10,13) and do the sorting? Here we know that we cannot just
write order(Mat[,c(1,3,6,8,10,13)]), which would give a wrong answer.

Thanks for any input.

Jessie

Yuyun Jessie Yang
Dissertator, Department of Statistics
University of Wisconsin-Madison

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