I'm having a few problems with using esApply. Simply I have my exprSey data split into groups. e.g. >pData(SE.exprs) sample group SE 100503.CEL 1 1 SE 240503.CEL 2 1 SE 100503.CEL 3 2 SE 240503.CEL 4 2 SE 100503.CEL 5 3 SE 240503.CEL 6 3 SE 100503.CEL 7 4 SE 240503.CEL 8 4 I want to use esApply and the dist function to calculate "maximum" distances between any given group (for a simple filtering routine). So.. >maxdiff<-function(x) + { + x<-as.data.frame(split(x,group)) ## gives me a list object x like $"1007_s_at" cMSC MAPC MSC rcMSC SE cMSC 28f 100503.CEL 8.675171 8.607033 8.973225 8.805668 SE CMSC 40YMALE 240503.CEL 8.681846 8.578437 8.868079 8.509754 ... etc. ## so then I wish to calculate the distances (max) between columns/groups + dist(t(x),"maximum")} ## and use esApply to calculate it for each gene >esApply(SE.exprs,1, maxdiff) Error in array(ans, c(len.a%/%d2, d.ans), if (is.null(dn.ans)) { : length of dimnames[1] not equal to array extent # gives an error because it's a list-- obviously I can extract it using # t(x$1007_s_at) for the first case but how do I do this for each and every # case? # or simply is their another function to coerce the vector x into a # data.frame without going through a list. I hope that's clear! Stephen Henderson WIBR ********************************************************************** This email and any files transmitted with it are confidential an... {{dropped}}