[datatable-help] setkey removes attribute settings

[Matthew Dowle]

... and I added a comment and link back to this thread, to this FR :
https://r-forge.r-project.org/tracker/index.php?func=detail&aid=1006&group_id=240&atid=978
setkey doesn't retain user attributes because it (currently) copies the
data.table, something we'd like to improve anyway.
Matthew

On Wed, 2011-06-08 at 22:34 -0400, Steve Lianoglou wrote:
> Hi,
> 
> On Wed, Jun 8, 2011 at 7:01 PM, Thell Fowler <tbfowler4 at gmail.com> wrote:
> >
> > It looks like custom attributes are lost by a DF to DT creation, and when the key info for a DT is invalidated, altered, etc...  I ran into this when trying to attach some attribute info to a table that identifies column groups so that a new global variable or passing another param to functions wouldn't be needed.  This worked nicely, until I had need to either modify some data in the table, which invalidates the key...
> >
> > Was this a design decision?  If so, why?
> 
> Try `as.data.table` for a more "delicate" way to convert a data.frame
> to a data.table. Your attributes will come through to the other side.
> 
> R> df <- data.frame( id=c(1:5), name= letters[1:5] )
> R> attr(df, 'testing') <- 'keep me'
> R> dt <- as.data.table(df)
> R> attr(dt, 'testing')
> [1] "keep me"
> 
> -steve
> 
> >
> > Example::
> >
> > > df <- data.frame( id=c(1:5), name= letters[1:5] )
> >
> > > attr(df, 'testing') <- 'keep me'
> >
> > > attr(df, 'testing')
> > [1] "keep me"
> >
> > > dt <- data.table( df )
> > > attr(dt, 'testing')
> >
> > NULL
> > > attr(dt, 'testing') <- 'keep me'
> >
> > > attr(dt, 'testing')
> > [1] "keep me"
> >
> > > df[ 5 , 'id' ] <- 53
> > > dt[ 5 , 'id' ] <- 53
> >
> > > attr(df, 'testing')
> > [1] "keep me"
> >
> > > attr(dt, 'testing')
> > [1] "keep me"
> >
> > > setkey(dt)
> > > attr(dt, 'testing')
> >
> > NULL
> > > attr(dt, 'testing') <- 'keep me'
> >
> > > attr(dt, 'testing')
> > [1] "keep me"
> >
> > > dt[ 5 , 'id' ] <- 3
> > > attr(dt, 'testing')
> >
> > [1] "keep me"
> > > key(dt)
> > NULL
> >
> > >
> > --
> > Sincerely,
> > Thell
> >
> > _______________________________________________
> > datatable-help mailing list
> > datatable-help at lists.r-forge.r-project.org
> > https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/datatable-help
> >
> 
> 
> 
> --
> Steve Lianoglou
> Graduate Student: Computational Systems Biology
>  | Memorial Sloan-Kettering Cancer Center
>  | Weill Medical College of Cornell University
> Contact Info: http://cbio.mskcc.org/~lianos/contact
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