[datatable-help] unique.data.frame should create a copy, right?

[Ricardo Saporta]

Steve, great stuff!!
thanks for making that happen
<saporta at rutgers.edu>

Rick


On Wed, Aug 14, 2013 at 8:30 PM, Steve Lianoglou <
mailinglist.honeypot at gmail.com> wrote:

> Hi all,
>
> As I needed this sooner than I had expected, I just committed this
> change. It's in svn revision 889.
>
> I chose 'by.columns' as the parameter names -- seemed to make more
> sense to me, and using the short hand interactively saves a letter,
> eg: unique(dt, by=c('some', 'columns')) ;-)
>
> Here's the note from the NEWS file:
>
> o  "Uniqueness" tests can now specify arbirtray combinations of
> columns to use to test for duplicates. `by.columns` parameter added to
> unique.data.table and duplicated.data.table. This allows the user to
> test for uniqueness using any combination of columns in the
> data.table, where previously the user only had the option to use the
> keyed columns (if keyed) or all columns (if not). The default behavior
> sets `by.columns=key(dt)` to maintain backward compatability. See
> man/duplicated.Rd and tests 986:991 for more information. Thanks to
> Arunkumar Srinivasan, Ricardo Saporta, and Frank Erickson for useful
> discussions.
>
> Should work as advertised assuming my unit tests weren't too simplistic.
>
> Cheers,
>
> -steve
>
>
>
>
> On Tue, Aug 13, 2013 at 1:24 PM, Steve Lianoglou
> <mailinglist.honeypot at gmail.com> wrote:
> > Thanks for the suggestions, folks.
> >
> > Matthew: do you have a preference?
> >
> > -steve
> >
> > On Mon, Aug 12, 2013 at 11:12 AM, Ricardo Saporta
> > <saporta at scarletmail.rutgers.edu> wrote:
> >> Steve,
> >>
> >> I like your suggestion a lot.  I can see putting column specification to
> >> good use.
> >>
> >> As for the argument name, perhaps
> >>    'use.columns'
> >>
> >> And where a value of NULL or FALSE will yield same results as
> >> `unique.data.frame`
> >>
> >>     use.columns=key(x)   # default behavior
> >>     use.columns=c("col1name", "col7name")   #etc
> >>     use.columns=NULL
> >>
> >>
> >> Thanks as always,
> >> Rick
> >>
> >>
> >>
> >> On Mon, Aug 12, 2013 at 1:51 PM, Steve Lianoglou
> >> <mailinglist.honeypot at gmail.com> wrote:
> >>>
> >>> Hi folks,
> >>>
> >>> I actually want to revisit the fix I made here.
> >>>
> >>> Instead of having `use.key` in the signature to unique.data.table (and
> >>> duplicated.data.table) to be:
> >>>
> >>> function(x,
> >>>              incomparables=FALSE,
> >>>              tolerance=.Machine$double.eps ^ 0.5,
> >>>              use.key=TRUE, ...)
> >>>
> >>> How about we switch out use.key for a parameter that specifies the
> >>> column names to use in the uniqueness check, which defaults to key(x)
> >>> to keep backwards compatibility.
> >>>
> >>> For argument's sake (like that?), lets call this parameter `columns`
> >>> (by.columns? with.columns? whatever) so:
> >>>
> >>> function(x,
> >>>              incomparables=FALSE,
> >>>              tolerance=.Machine$double.eps ^ 0.5,
> >>>              columns=key(x), ...)
> >>>
> >>> Then:
> >>>
> >>> (1) leaving it alone is the backward compatibile behavior;
> >>> (2) Perhaps setting it to NULL will use all columns, and make it
> >>> equivalent to unique.data.frame (also the same when x has no key); and
> >>> (3) setting it to any other combo of columns uses those columns as the
> >>> uniqueness key and filters the rows (only) out of x accordingly.
> >>>
> >>> What do you folks think? Personally I think this is better on all
> >>> accounts then just specifying to use the key or not and the only
> >>> question in my mind is the name of the argument -- happy to hear other
> >>> world views, however, so don't be shy.
> >>>
> >>> Thanks,
> >>> -steve
> >>>
> >>> --
> >>> Steve Lianoglou
> >>> Computational Biologist
> >>> Bioinformatics and Computational Biology
> >>> Genentech
> >>
> >>
> >
> >
> >
> > --
> > Steve Lianoglou
> > Computational Biologist
> > Bioinformatics and Computational Biology
> > Genentech
>
>
>
> --
> Steve Lianoglou
> Computational Biologist
> Bioinformatics and Computational Biology
> Genentech
>
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