R help - Oct 2014 - Obtain a list of data tables from a main data table

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)]

 

Thank
you very much to all the members!

 		 	   		  
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I thought the whole purpose of data.table was to allow group data processing
without creating oodles of separate tables.

What is your intended use of ask if these tables?
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On October 8, 2014 9:06:30 AM MDT, "Frank S." <f_j_rod at
hotmail.com> 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)]
>
> 
>
>Thank
>you very much to all the members!
>
> 		 	   		  
>	[[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.

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