[R] ddply/tapply and set function

[Bert Gunter]

df <- data.frame(X1 = c(1,1,1,2,2), X2 = c(1,5,7,3,8))
> df
  X1 X2
1  1  1
2  1  5
3  1  7
4  2  3
5  2  8
> v <- with(df, tapply(X2, X1, c))
## v is a list, and I would work directly with this rather than converting
to a data.frame. But if you insist:

> df2 <- data.frame(v, row.names = names(v))
> df2[1,1] ## produces a **list** with a single component containing the
vector c(1,5,7)
[[1]]
[1] 1 5 7

> df2[[1,1]] ## produces a vector -- note doubled brackets
[1] 1 5 7


Cheers,
Bert Gunter

"The trouble with having an open mind is that people keep coming along and
sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )


On Wed, Feb 17, 2021 at 6:50 AM A. Mani <a.mani.cms using gmail.com> wrote:

> The original data frame can be like
> Type   Id
> 1         1
> 1         5
> 1         7
> 2         3
> 2         8
> ..        ....
>
> tapply(Id,Type,set) will yield the sets correctly (assuming the data
> frame is attached) but not a data frame of the form mentioned.
>
> A similar ddply command does not work at all with the function 'set'
> (while 'mean' etc work fine)
>
> Thanks and Best
>
> A Mani
>
> Prof.Dr.(Miss) A Mani
> ASL, AMS, ISRS, CLC, CMS, MTA
> Senior Member, International Rough Set Society
> Research Scientist, Indian Statistical Institute, Kolkata
> Formerly HBCSE, TIFR, CU.
> Homepage: https://www.logicamani.in
> Blog: https://logicamani.blogspot.in/
> Research Gate: https://www.researchgate.net/profile/Mani_A
> sip:girlprofessor using ekiga.net
> Pronouns: She/Her/Hers
>
> On Wed, Feb 17, 2021 at 4:24 PM Jim Lemon <drjimlemon using gmail.com> wrote:
> >
> > Hi  A,
> > I'm unable to work out what you are using as input. Maybe:
> >
> > id<-data.frame(Type=c(1,2,1,1,2),set=c(1,3,5,7,8))
> >
> > but that doesn't work with your
> >
> > tapply(id,Type,set)
> >
> > command. Perhaps a bit more detail?
> >
> > Jim
> >
> >
> >
> > On Wed, Feb 17, 2021 at 7:48 PM A. Mani <a.mani.cms using gmail.com> wrote:
> > >
> > > I want a data frame (derived from another data frame) of the form
> > >
> > > Type   Set
> > > 1         {1,5, 7}
> > > 2         {3,8)
> > > ..        ....
> > >
> > > tapply(Id,Type, set) works, but does not yield a data frame.
> > > 'set' is from package set/set6/etc
> > > ddply does not seem to work with the function.
> > > How should I proceed with this optimally?
> > >
> > >
> > > Thanks and Best
> > >
> > > A Mani
> > >
> > > Prof.Dr.(Miss) A Mani
> > > ASL, AMS, ISRS, CLC, CMS, MTA
> > > Senior Member, International Rough Set Society
> > > Research Scientist, Indian Statistical Institute, Kolkata
> > > Formerly HBCSE, TIFR, CU.
> > > Homepage: https://www.logicamani.in
> > > Blog: https://logicamani.blogspot.in/
> > > Research Gate: https://www.researchgate.net/profile/Mani_A
> > > sip:girlprofessor using ekiga.net
> > > Pronouns: She/Her/Hers
> > >
> > > ______________________________________________
> > > R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> > > 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.
>
> ______________________________________________
> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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.
>

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