Currently each cdf package comes with two 'mapping' functions xy2i() and i2xy(), which can be used to map (x, y) coordinates of a chip to indices and vice versa. These functions appear not to be used much, and tend to be masked upon loading of a second cdf package. In addition, there are safer functions xy2indices() and indices2xy() in the affy package that can be used for the same purpose. For these reasons, we are planning to deprecate these functions in the coming release (BioC 2.0) and they will be defunct in the subsequent release (BioC 2.1). Best, Jim -- James W. MacDonald, M.S. Biostatistician Affymetrix and cDNA Microarray Core University of Michigan Cancer Center 1500 E. Medical Center Drive 7410 CCGC Ann Arbor MI 48109 734-647-5623 ********************************************************** Electronic Mail is not secure, may not be read every day, and should not be used for urgent or sensitive issues.