R help - Apr 2011 - Assigning a larger number of levels to a factor that has fewer levels

Hello!

I have larger and a smaller data frame with 1 factor in each - it's
the same factor:

large.frame<-data.frame(myfactor=LETTERS[1:10])
small.frame<-data.frame(myfactor=LETTERS[c(9,7,5,3,1)])
levels(large.frame$myfactor)
levels(small.frame$myfactor)
table(large.frame$myfactor)
table(small.frame$myfactor)

myfactor has 10 levels in large.frame and 5 levels in small.frame. All
5 levels in small.frame are present in large.frame.
How could I make levels(small.frame$myfactor) contain all the same
levels as levels(large.frame$myfactor)?
In other words, I want table(small.frame$myfactor) to have the same
number of entries as table(small.frame$myfactor) but with 5 zeros in
it:
A B C D E F G J I J
1 0 1 0 1 0 1 0 1 0

Thank you very much for your suggestions!
-- 
Dimitri Liakhovitski
Ninah Consulting
www.ninah.com

Hi Dimitri,
The factor() function allows you to specify the levels. So

small.frame$myfactor <- factor(small.frame$myfactor, levels
levels(large.frame$myfactor))

should do it.

Best,
Ista

On Thu, Apr 7, 2011 at 11:47 AM, Dimitri Liakhovitski
<dimitri.liakhovitski at gmail.com> wrote:
> Hello!
>
> I have larger and a smaller data frame with 1 factor in each - it's
> the same factor:
>
> large.frame<-data.frame(myfactor=LETTERS[1:10])
> small.frame<-data.frame(myfactor=LETTERS[c(9,7,5,3,1)])
> levels(large.frame$myfactor)
> levels(small.frame$myfactor)
> table(large.frame$myfactor)
> table(small.frame$myfactor)
>
> myfactor has 10 levels in large.frame and 5 levels in small.frame. All
> 5 levels in small.frame are present in large.frame.
> How could I make levels(small.frame$myfactor) contain all the same
> levels as levels(large.frame$myfactor)?
> In other words, I want table(small.frame$myfactor) to have the same
> number of entries as table(small.frame$myfactor) but with 5 zeros in
> it:
> A B C D E F G J I J
> 1 0 1 0 1 0 1 0 1 0
>
> Thank you very much for your suggestions!
> --
> Dimitri Liakhovitski
> Ninah Consulting
> www.ninah.com
>
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> and provide commented, minimal, self-contained, reproducible code.
>


-- 
Ista Zahn
Graduate student
University of Rochester
Department of Clinical and Social Psychology
http://yourpsyche.org