Hi Martin, I am not sure who I should contact with for this problem. I just send this to you. The problem is: when I try to combine two numeric types (integer and double) of matrix (actually they are in the assayData of ExpressionSet), the combine function reports error. For example: a = matrix(rnorm(10), 2) # set rownames and colnames because combine function require it. colnames(a) = LETTERS[1:5]; rownames(a) = 1:2 b = matrix(1:10, 2) colnames(b) = LETTERS[6:10]; rownames(b) = 1:2 combine(a, b) > Error in combine(a, b) : matrix types double, integer differ I suppose the combine function should automatically convert the integer as double before combining them because this situation can be met very often. What's your suggestion? Thanks! Have a nice day! Pan