Thank you all for the help and solutions presented!
Luisa

On Thu, May 19, 2011 at 9:33 PM, Dennis Murphy <djmuser@gmail.com> wrote:

> Oops, didn't see Marc's reply. His solution is much more compact. For
> R 2.11.0 and above, aggregate() now has a formula interface that
> usually works nicely:
>
> aggregate(Var3 ~ Var1 + Var2, data = d, FUN = table)
>   Var1 Var2 Var3.D Var3.I
> 1   S1   T1      2      2
> 2   S2   T1      2      2
> 3   S1   T2      2      2
> 4   S2   T2      0      4
>
> Dennis
>
> On Thu, May 19, 2011 at 12:29 PM, Dennis Murphy <djmuser@gmail.com> wrote:
> > Hi:
> >
> > The dummy column really isn't necessary. Here's another way to get the
> > result you want. Let d be the name of your example data frame.
> >
> > d <- d[, 1:3]
> > (dtable <- as.data.frame(ftable(d, row.vars = c(1, 2))))
> >  Var1 Var2 Var3 Freq
> > 1   S1   T1    D    2
> > 2   S2   T1    D    2
> > 3   S1   T2    D    2
> > 4   S2   T2    D    0
> > 5   S1   T1    I    2
> > 6   S2   T1    I    2
> > 7   S1   T2    I    2
> > 8   S2   T2    I    4
> >
> > An alternative to the reshape() function is the reshape2 package,
> > which has a function dcast() that allows you to rearrange the data
> > frame as you desire.
> >
> > library(reshape2)
> > dcast(dtable, Var1 + Var2 ~ Var3)
> > Using Freq as value column: use value_var to override.
> >  Var1 Var2 D I
> > 1   S1   T1 2 2
> > 2   S1   T2 2 2
> > 3   S2   T1 2 2
> > 4   S2   T2 0 4
> >
> >
> > HTH,
> > Dennis
> >
> > On Thu, May 19, 2011 at 2:13 AM, Luma R <rluma1979@gmail.com> wrote:
> >> Dear all,
> >>
> >> I am having trouble creating summary tables using aggregate function.
> >>
> >> given the following table:
> >>
> >>
> >> Var1   Var2    Var3   dummy
> >> S1       T1         I         1
> >> S1       T1         I         1
> >> S1       T1         D        1
> >> S1       T1         D        1
> >> S1       T2         I         1
> >> S1       T2         I         1
> >> S1       T2         D        1
> >> S1       T2         D        1
> >> S2       T1         I         1
> >> S2       T1         I         1
> >> S2       T1         D        1
> >> S2       T1         D        1
> >> S2       T2         I         1
> >> S2       T2         I         1
> >> S2       T2         I        1
> >> S2       T2         I        1
> >>
> >>
> >> I want to create a summary table that shows for each category of Var1,
> >> Var2, the number of cells that are Var3=D and Var3-I :
> >>
> >>         Var1 Var2  Var3(D)   Var3(I)
> >>         S1     T1    2              2
> >>         S1     T2    2              2
> >>         S2     T1    2              2
> >>         S2     T2    0              4
> >>
> >>
> >>
> >> However, if I do: Count.Cells=  aggregate(dummy~ Var1+Var2+Var3,
> FUN='sum')
> >> , I get:
> >>
> >>           Var1 Var2  Var3 Count of Resp
> >>            S1     T1     D        2
> >>            S1     T1     I          2
> >>            S1     T2     D        2
> >>            S1     T2     I         2
> >>            S2     T1     D       2
> >>            S2      T1    I        2
> >>            S2     T2     I        4
> >>
> >>
> >> Is there a way to get different columns for each Var3 level?
> >>
> >>
> >> Thank you for any help you can give!
> >>
> >>        [[alternative HTML version deleted]]
> >>
> >> ______________________________________________
> >> R-help@r-project.org mailing list
> >> 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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