R help - May 2009 - re shape package - use one cast() instead of many

I have a data set that I'm trying to melt and cast in a specific way using
the reshape package. (I'll use the ff_d dataset from reshape so I don't
have
to post a toy data set here. )

Lets say I'm looking for the interaction of treatment with each type of
"variable" in ff_d. Using the command below gets me this. Subject will
get a
column and each treatment type by each variable will also get a column with
values for each.

cast(ff_d, subject~treatment+variable)
   subject 1_potato 1_buttery 1_grassy 1_rancid 1_painty 2_potato 2_buttery
....  3_painty
1        3       18        18       18       18       18       18        18
....   18
...

Now, if I want to look at just the  the values for each variable by subject
I can run the following command.
cast(ff_d, subject~variable)
   subject potato buttery grassy rancid painty
1        3     54      54     54     54     54
...

What I'm wondering now, is run one cast() call and get both of these in one
data.frame? Essentially, the values for each separate "condition" and
interactions between them? cast() doesn't let me repeat variable names as
that's what I first tried.  Right now, i'm just running two separate
cast()
calls and cbinding/merging them together. Is there a better way?  
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On Tue, May 5, 2009 at 3:03 PM, jwg20 <jason.gullifer at gmail.com>
wrote:
>
> I have a data set that I'm trying to melt and cast in a specific way
using
> the reshape package. (I'll use the ff_d dataset from reshape so I
don't have
> to post a toy data set here. )
>
> Lets say I'm looking for the interaction of treatment with each type of
> "variable" in ff_d. Using the command below gets me this. Subject
will get a
> column and each treatment type by each variable will also get a column with
> values for each.
>
> cast(ff_d, subject~treatment+variable)
> ? subject 1_potato 1_buttery 1_grassy 1_rancid 1_painty 2_potato 2_buttery
> .... ?3_painty
> 1 ? ? ? ?3 ? ? ? 18 ? ? ? ?18 ? ? ? 18 ? ? ? 18 ? ? ? 18 ? ? ? 18 ? ? ? ?18
> .... ? 18
> ...
>
> Now, if I want to look at just the ?the values for each variable by subject
> I can run the following command.
> cast(ff_d, subject~variable)
> ? subject potato buttery grassy rancid painty
> 1 ? ? ? ?3 ? ? 54 ? ? ?54 ? ? 54 ? ? 54 ? ? 54
> ...
>
> What I'm wondering now, is run one cast() call and get both of these in
one
> data.frame? Essentially, the values for each separate "condition"
and
> interactions between them? cast() doesn't let me repeat variable names
as
> that's what I first tried. ?Right now, i'm just running two
separate cast()
> calls and cbinding/merging them together. Is there a better way?
Have a look at the margins argument.

Hadley


-- 
http://had.co.nz/