ddply/tapply and set function

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 at 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 at ekiga.net
Pronouns: She/Her/Hers

On Wed, Feb 17, 2021 at 4:24 PM Jim Lemon <drjimlemon at 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 at 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 at ekiga.net
Pronouns: She/Her/Hers