[R] Loop over several variables

[Jan van der Laan]

Or

ti <- aggregate(dataframename[paste0("y", 1:3)],
         by=dataframename["aggregationvar"],
         sum,na.rm=TRUE)

which gives you all results in one data.frame.

Jan



"MacQueen, Don" <macqueen1 at llnl.gov> schreef:

> Many ways. Here is one:
>
> ### supposing you have y1, y2, and y3 in your data frame
>
> for (i in 1:3) {
>
>   yi <- paste('y',i,sep='')
>
>   ti <- aggregate(dataframename[[yi]],
>            by=data.frame(dataframename$aggregationvar),
>            sum,na.rm=TRUE)
>
>   assign( paste('ti',i,sep='') , ti, '.GlobalEnv')
> }
>
> Or if you happen to think using assign() is bad form you can store each ti
> in a list().
>
> -Don
>
>
> --
> Don MacQueen
>
> Lawrence Livermore National Laboratory
> 7000 East Ave., L-627
> Livermore, CA 94550
> 925-423-1062
>
>
>
>
>
> On 11/1/12 4:32 AM, "bchr" <bochristoph at web.de> wrote:
>
>> Hey everybody,
>>
>> I am looking for a way to loop commands over several variables in a
>> dataframe. Basically I want to do something like this:
>>
>> ti1<-aggregate(dataframename$y1,
>>               by=data.frame(dataframename$aggregationvar),
>>               sum,na.rm=TRUE)
>>
>> This works fine as it is but i want to do it for several variables thereby
>> generating several tix. I tried with a for-loop but the problem was that I
>> could neither find a way combine my indexnumber i (1 ... x) with the y or
>> ti
>> (as for example in Stata I could do by writing y`i')  nor did it work
>> using
>> a vector of string variables  ("y1", ... "yx") and looping over that
>> (while
>> using yx also as a name for the target dataframe instead of tix - i
>> would'nt
>> mind that).
>>
>> Preferably I would be looking for a solution that can do without any of
>> the
>> apply functions (yes, I know they are more R-like, but frankly, I don't
>> get
>> the logic behind them, so for the time being I would prefer another way)
>>
>> Tanks very much for your help
>>
>> Bernhard
>>
>>
>>
>> --
>> View this message in context:
>> http://r.789695.n4.nabble.com/Loop-over-several-variables-tp4648112.html
>> Sent from the R help mailing list archive at Nabble.com.
>>
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>
> ______________________________________________
> R-help at r-project.org mailing list
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.