[BioC] Average over probes that share the same clone ID in an expression matrix

[Sean Davis]

On Friday 30 March 2007 06:51, Daniel Brewer wrote:
> I have a matrix of expression values with the rows as probeIDs and the
> columns as sample names.  I have an associated annotation file with each
> row corresponding to the row in the expression matrix.  Some of the
> probe IDs share clone IDs.  What I would like to do is for the probes
> that share the same clone IDs I would like to find the median and
> replace the values in the matrix with the result.
>
> Does anyone know the most efficient way of doing this?

The aggregate() function is for doing this type of thing.  

Sean