Hi,

I am interested in using the cast function in R to perform some aggregation. I did once manage to get it working, but have now forgotten how I did this. So here is my dilemma. I have several thousands of probes (about 180,000) corresponding to each gene; what I'd like to do is obtain is a frequency count of the various occurrences of each probes for each gene.

The data would look something like this:

Gene     ProbeID               Expression_Level
A             1              0.34
A             2              0.21
E              3              0.11
A             4              0.21
F              5              0.56
F              6              0.87
.
.
.
(180000 data points)

In each case, the probeID is unique. The output I am looking for is something like this:

Gene     No.ofprobes      Mean_expression
A             3              0.25

Is there an easy way to do this using "cast" or "melt"? Ideally, I would also like to see the unique probes corresponding to each gene in the wide format.

Thanks in advance
Max

Maxy Mariasegaram| Reserach Fellow | Australian Prostate Cancer Research Centre| Level 1, Building 33 | Princess Alexandra Hospital | 199 Ipswich Road, Brisbane QLD 4102 Australia | t: 07 3176 3073| f: 07 3176 7440 | e: mariaseg@qut.edu.au


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