[R] 2 factor split and lapply

[Bert Gunter]

As I said, ?tapply gives you an answer (without using other packages) . Read it.

-- 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 Mon, Dec 23, 2013 at 6:22 AM, Onur Uncu <onuruncu at gmail.com> wrote:
> 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]]
>>>
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