2 factor split and lapply

Sure, here is a reproducible example:

testframe<-data.frame(factor1=c("a","b","a"),factor2=c(1,2,2),data=c(3.34,4.2,2.1))

splitframe<-split(testframe,list(factor1=testframe$factor1,factor2=testframe$factor2))

lapply(splitframe,function(x)mean(x[,"data"]))

The above lapply returns

$a.1
[1] 3.34

$b.1
[1] NaN

$a.2
[1] 2.1

$b.2
[1] 4.2

The results are correct but not presented in a format I prefer... Factor1 and factor2 are combined into a single factor, which is not desired. I want to keep them seperate. Ideally, a table output as below.

     a          b
1   3.34     NaN
2   2.1       4.2

How can I achieve this please?

On 23 Dec 2013, at 00:44, Bert Gunter <gunter.berton at gene.com> wrote:

I believe you missed
?tapply
which does what you want I think (in the absence of a reproducible
example one cannot be sure).

Cheers,
Bert



Bert Gunter
Genentech Nonclinical Biostatistics
(650) 467-7374

"Data is not information. Information is not knowledge. And knowledge
is certainly not wisdom."
H. Gilbert Welch

On Sun, Dec 22, 2013 at 3:54 PM, Onur Uncu <onuruncu at gmail.com> wrote:
R Users,

I have a data frame which I split using 2 factors using the split function:

split(datframe, list(f=factor1, f2=factor2));

I then used lapply to get some summary statistics grouped by factor1 and
factor2.

I now want to change the appearance of this output. I want to get  a 2
dimensional table where columns represent values of factor1, rows represent
values of factor2 and the entries on the table represent the summary
results that were calculated by lapply.

I tried as.table() function but did not help. It seems the problem is that
R combined factor1 and factor 2 into one factor when I used list(f=factor1,
f2=factor2) in the split function. So R is now unable to treat them as 2
different factors in order to put them on row and columns of a table... Any
ideas how I can achieve the desired table?

Thanks for your help.

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