I don't remember discussing this issue...? What is the conceptual difference between dt[, a] and dt[, "a", with = F] and what does 'drop' have to do with this??
On Fri, May 17, 2013 at 10:02 AM, Arunkumar Srinivasan < [email protected]> wrote: > Eduard, are we discussing the same thing again :)? Wasn't this somehow > your question as well.. the discrepancy between: > > dt[, a] and dt[, "a", with=FALSE]. > > There should be a drop=TRUE/FALSE option (as in the case of data.frame) > that should be used when you use `with=FALSE`. Until then, the default > option seems to be drop=FALSE, which results in a data.table. > > Alexandre, as of now, it could be done as Eduard points out. > > Arun > > On Friday, May 17, 2013 at 4:59 PM, Eduard Antonyan wrote: > > Use dt[[colname]], but this seems like a bug to me - I would've thought > that dt[, a] and dt[, "a", with = F] should return the exact same thing. > > > On Fri, May 17, 2013 at 9:42 AM, Alexandre Sieira < > [email protected]> wrote: > > Sorry if this is a basic question. > > > I'm using R 3.0.0 and data.table 1.8.8. The documentation for 'j' states > that "A single column or single expression returns that type, usually a > vector." > > > I am able to obtain this behavior if I know the column name in advance: > > > > dt = data.table(a=c(1, 2, 3), b=c(4, 5, 6)) > > > dt > > a b > > 1: 1 4 > > 2: 2 5 > > 3: 3 6 > > > str(dt[,a]) > > num [1:3] 1 2 3 > > > However, if I don't, no such luck: > > > colname="a" > > str(dt[,colname,with=F]) > Classes ‘data.table’ and 'data.frame': 3 obs. of 1 variable: > $ a: num 1 2 3 > - attr(*, ".internal.selfref")=<externalptr> > > If there a way to extract an entire column as a vector if I have the > column name as a character scalar? > > Thank you! > > -- > Alexandre Sieira > CISA, CISSP, ISO 27001 Lead Auditor > > "The truth is rarely pure and never simple." > Oscar Wilde, The Importance of Being Earnest, 1895, Act I > > _______________________________________________ > datatable-help mailing list > [email protected] > https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/datatable-help > > > _______________________________________________ > datatable-help mailing list > [email protected] > https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/datatable-help > > >
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