[R] 2 factor split and lapply

[Onur Uncu]

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.
>> 
>>        [[alternative HTML version deleted]]
>> 
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.