[BioC] mean of individual rows for subsets of columns in an ExprSet

[Anna Gustafsson]

Dear all,

I am sorry to disturb with yet a simple question but I have tried my best and have now given up on solving it myself... :(

I wonder if somebody knows how I easily can create mean values and their SD from subsets of columns (representing cases) over all rows individually (representing the genes) from an object - eset - (which is an Expression Set with 12625 genes, 7 samples).
E.g the mean and SD from all rows individually in columns 4,5,6 and 7 of my data?

Grateful for help!

// Anna :o)