Hi Nils,
have a look at
?tapply
hth.
Am 09.07.2010 15:37, schrieb LogLord:
> Hi,
>
> I would like to assign the largest value of a column to a specific category
> and repeat this for each column (v1 - v4).
>
>
>> x=c(1:12)
>> cat=c("cat1","cat5","cat2","cat2","cat1","cat5","cat3","cat4","cat5","cat2","cat3","cat6")
>> v1=rnorm(12,0.5,0.1)
>> v2=rnorm(12,0.3,0.2)
>> v3=rnorm(12,0.4,0.1)
>> v4=rnorm(12,0.6,0.3)
>> bla=data.frame(x,cat,v1,v2,v3,v4)
>> bla
>>
> x cat v1 v2 v3 v4
> 1 1 cat1 0.4013144 0.54839317 0.3946393 0.8679266
> 2 2 cat5 0.4595873 0.45788906 0.4030078 0.5919596
> 3 3 cat2 0.4542865 0.21516928 0.2777649 0.6112099
> 4 4 cat2 0.4787950 0.06252512 0.5095611 0.6450795
> 5 5 cat1 0.4910746 0.56591049 0.5151813 0.8465181
> 6 6 cat5 0.4194397 0.16592579 0.4361643 0.6415192
> 7 7 cat3 0.6148564 0.32240342 0.2690108 0.7114133
> 8 8 cat4 0.6174652 0.28076152 0.4577064 -0.2567284
> 9 9 cat5 0.4775395 0.28611768 0.4660210 0.4634120
> 10 10 cat2 0.4802962 0.03715569 0.4506361 1.0063235
> 11 11 cat3 0.6495094 0.33303172 0.3352933 1.4390324
> 12 12 cat6 0.4891481 0.45355589 0.3880739 0.7831656
>
>>
> I can assign this by the sqldf() command for each column but I would like to
> automate this as I have many columns.
>
>
>> select=sqldf("select cat, max(v1) FROM bla GROUP BY cat")
>> select
>>
> cat max(v1)
> 1 cat1 0.4910746
> 2 cat2 0.4802962
> 3 cat3 0.6495094
> 4 cat4 0.6174652
> 5 cat5 0.4775395
> 6 cat6 0.4891481
>
>>
> Finally, I would like to have a dataframe where where the cat is followed by
> each column maximum.
>
> Thanks for your help!
>
--
Eik Vettorazzi
Institut für Medizinische Biometrie und Epidemiologie
Universitätsklinikum Hamburg-Eppendorf
Martinistr. 52
20246 Hamburg
T ++49/40/7410-58243
F ++49/40/7410-57790
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