[R] trouble with summary tables with several variables using aggregate function

[Dennis Murphy]

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 at 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]]
>
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