find the unique rows in a matrix

Description

This routine returns a matrix containing all the unique rows of the matrix supplied as its argument. That is, all the duplicate rows are stripped out. Note that the ordering of the rows on exit is not the same as on entry.

Usage

uniquecombs(x)

Arguments

Details

Models with more parameters than unique combinations of covariates are not identifiable. This routine provides a means of evaluating the number of unique combinations of coavariates in a model. The routine calls compiled C code.

Value

A matrix consisting of the unique rows of x (in arbitrary order).

Author(s)

Simon N. Wood simon.wood@r-project.org

Examples

X<-matrix(c(1,2,3,1,2,3,4,5,6,1,3,2,4,5,6,1,1,1),6,3,byrow=TRUE)
print(X)
uniquecombs(X)