Hi,when I perform SAM on my array data(siggenes)I have some problems in retrieving the separate lists of up regulated and down regulated genes. When I write: fold<-function(x){ gruppi<-split(x,controllo) geni1<-abs(mean(gruppi[[2]])-mean(gruppi[[1]])) return(geni1) } fold<-esApply(expr.contr.tratt.4,1,fold) filtro.geni.4_prova<-expr.contr.tratt.4[which(fold>=1),] filtro.geni.4_prova everything is working well and I can obtain the correct HTML output,but if I write the same using fold change<1 to obtain downregulated genes,I have the following warning message: ###Warning messages: ####1: the condition has length > 1 and only the first element will be used in: if (!nchar(text <- getText(object))) return("") ####2: the condition has length > 1 and only the first element will be used in: if (!nchar(text <- getText(object))) return("") ####3: the condition has length > 1 and only the first element will be used in: if (!nchar(text <- getText(object))) return("") ####4: the condition has length > 1 and only the first element will be used in: if (!nchar(text <- getText(object))) return("") ####5: the condition has length > 1 and only the first element will be used in: if (!nchar(text <- getText(object))) return("") Where is the mistake? Thank you for your help Sara