[R] polynomial contrasts in R

George W. Gilchrist gwgilc at wm.edu
Thu Jan 16 23:20:03 CET 2003

In S-Plus, I can obtain polynomial contrasts for an ordered factor with
contr.poly(). The function also exists in R, however is limited to factors
where the levels are equally spaced. In S-Plus, one can obtain the contrasts
for a set of numeric values representing unequally spaced ordered factors.
Has anyone implemented this in R? I see that the S-Plus function calls
another function (poly.raw()) that calls a Fortran routine. Thanks for your

Cheers, George

George W. Gilchrist                        Email #1: gwgilc at wm.edu
Department of Biology, Box 8795          Email #2: kitesci at cox.net
College of William & Mary                    Phone: (757) 221-7751
Williamsburg, VA 23187-8795                    Fax: (757) 221-6483

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