[R] Obtain a list of data tables from a main data table

[David Winsemius]

On Oct 8, 2014, at 8:06 AM, Frank S. wrote:

> 
> 
> Hi everybody,
> 
> 
> 
> I have (as an example) the following
> two data tables:
> 
> 
> 
> all <-
> data.table(ID = c(rep(c(100:105),c(3,2,2,3,3,3))),
> 
>     value =
> c(100,120,110,90,45,35,270,50,65,40,25,55,75,30,95,70))
> 
> DT <-
> data.table(ID = 100:105, code=c(2,1,3,2,3,1))
> 
> 
> 
> My aim is to construct as many sub data tables as different values for
> the integer variable code, and I have
> done:
> 
> code_1
> <- all[ID %in% DT[code==1]$ID] 
> 
> code_2
> <- all[ID %in% DT[code==2]$ID] 
> 
> code_3
> <- all[ID %in% DT[code==3]$ID] 
> 
> 
> 
> Because maximum code value can be very
> high, ¿is it possible to obtain a list of the above 3 data tables through a
> loop? I mean something like:
> 
> 
> 
> for (i in
> 1:max(DT$code)){
> 
>  paste(code,‚_‚,[i]) <- }
> 
> return(list)]

Why not use lapply (since it is designed to return a list) and call the subset function in the data.table package?

> 
> 
> 
> Thank
> you very much to all the members!
> 
> 		 	   		  
> 	[[alternative HTML version deleted]]

This is a plain text mailing list.

> ______________________________________________
> 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.

David Winsemius
Alameda, CA, USA