[R] transpose but different

[Gabor Grothendieck]

Try this.  First we use outer to form a matrix such that i,j-th entry
is TRUE if i, j are in the same group and unequal and FALSE otherwise.
 We apply which on the rows of that matrix to get the groups that are
associated with the row group.  We then cbind the components together
using ts class to prevent recycling and cbind that to a.  Finally we
remove the ugly rownames.  Note that if a has N rows then an NxN
matrix will be created

gps <- apply(outer(a$group, a$group, "==") & !diag(nrow(a)), 1, which)
out <- cbind(a, t(do.call(cbind, lapply(gps, ts))))
rownames(out) <- NULL

On Tue, Apr 13, 2010 at 8:04 AM, Duijvesteijn, Naomi
<Naomi.Duijvesteijn at ipg.nl> wrote:
>
>   Hi all,
>
>
>
>   I  want  to  make  extra  columns in my datafile where the id of every
>   groupmember is mentioned in separate columns. To explain it better see the
>   example:
>
>
>
>   id<-c(1,2,3,4,5,6,7,8,9,10,11,12)
>
>   group<-c(1,1,1,1,2,2,3,3,3,3,3,3)
>
>   a<-as.data.frame(cbind(id,group))
>
>   a
>
>      id group
>
>   1   1     1
>
>   2   2     1
>
>   3   3     1
>
>   4   4     1
>
>   5   5     2
>
>   6   6     2
>
>   7   7     3
>
>   8   8     3
>
>   9   9     3
>
>   10 10     3
>
>   11 11     3
>
>   12 12     3
>
>
>
>   Result should be (gm = groupmember)
>
>
>   id  group   gm1         gm2       gm3      gm4           gm5       gm6
>     gm7            etc.
>
>   1     1          2             3           4          NA            NA
>   NA            NA
>
>   2     1          1             3           4          NA            NA
>   NA            NA
>
>   3     1          1             2           4          NA            NA
>   NA            NA
>
>   4     1          1             2           3          NA            NA
>   NA            NA
>
>   5     2          6             NA          NA        NA             NA
>   NA            NA
>
>   6     2          5             NA          NA        NA             NA
>   NA            NA
>
>   7     3          8            9           10          11            12
>     NA             NA
>
>   8        3            7               9              10             11
>   12          NA             NA
>
>   9        3            7               8              10             11
>   12          NA             NA
>
>   10       3            7               8              9              11
>   12          NA             NA
>
>   11       3            7               8              9              10
>   12          NA             NA
>
>   12       3            7               8              9              10
>   11          NA             NA
>
>
>
>   What I have been trying so far is reshape, but this doesn’t put the id’s of
>   the groupmembers of different groups under the same columnname. It makes new
>   columnnames per group.
>
>
>   Couls somebody help me out with this? I really appreciate it
>
>
>   Regards,
>
>   Naomi Duijvesteijn
>
>
>
>
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