Hi,
You can get it with "by":
foo <- function(x)c(length(x$probe), mean(x$exp))
res <- by(df[c('exp', 'probe')], df['gene'], FUN=foo)
do.call(rbind, res)
Bye,
Oscar.
--
Oscar Perpiñán Lamigueiro
Dpto. Ingeniería Eléctrica
EUITI-UPM
http://procomun.wordpress.com
El Thu, 30 Jun 2011 17:28:02 +1000
Max Mariasegaram <max.mariasega...@qut.edu.au> escribió:
> 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: maria...@qut.edu.au
>
>
> [[alternative HTML version deleted]]
>
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