[R] 'asymmetric span' for 2D loess?

From: Tokuyasu, Taku <Tokuyasu_at_cc.ucsf.edu>
Date: Mon, 02 Jun 2008 22:52:35 -0700


I am interested in performing a 2D loess smooth on microarray data, i.e. log2 ratios on a 2D grid, using different spans in the horizontal and vertical directions (the immediate reason being that replicate spots are laid out in the horizontal direction). Is it possible to do this in R? Functions like loess(stats) seem to apply the same span for all predictors, which carries over to functions like ma2D(marray).

As an elementary second question, are there circumstances where one expects to see a substantial difference in the fits between say loess(y ~ x1 + x2) and loess(y ~ x1 * x2) with an interaction term (and if so, what are they)?

Many thanks,


Taku A. Tokuyasu, PhD
UCSF Helen Diller Family Comprehensive Cancer Center
San Francisco, CA 94143-0808

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