R help - Aug 2009 - Convert dataframe to table with counts where column names become row names

Can anyone explain how best to go from a dataframe to a table (or better yet
a new dataframe) of counts, where the row names in the new table (or
dataframe) are the column names of the original df.

start w/
DF1 = 
           Pos1  Pos2 Pos3 ....
oligo1   G       C     A
oligo2   U       U     A
oligo3   G       C     C
oligo4   C       G     U
oligo5   A       A     G
.....

End with 

DF2 = 
           G  A  U C
Pos1   2   1 1 1
Pos2   1  1  1  2
Pos3  1  2  1  1
....

I know how to generate the counts of each one column at a time using
"table(DF1$Pos1)".
Is there a way to do this in one step?  Should I just write a for loop for
each of the columns?

thanks,

greg
-- 
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Try this:
t(sapply(DF1, table))

On Thu, Aug 6, 2009 at 2:14 PM, ghinkle <ghinkle@alnylam.com> wrote:
>
> Can anyone explain how best to go from a dataframe to a table (or better
> yet
> a new dataframe) of counts, where the row names in the new table (or
> dataframe) are the column names of the original df.
>
> start w/
> DF1 >           Pos1  Pos2 Pos3 ....
> oligo1   G       C     A
> oligo2   U       U     A
> oligo3   G       C     C
> oligo4   C       G     U
> oligo5   A       A     G
> .....
>
> End with
>
> DF2 >           G  A  U C
> Pos1   2   1 1 1
> Pos2   1  1  1  2
> Pos3  1  2  1  1
> ....
>
> I know how to generate the counts of each one column at a time using
> "table(DF1$Pos1)".
> Is there a way to do this in one step?  Should I just write a for loop for
> each of the columns?
>
> thanks,
>
> greg
> --
> View this message in context:
>
http://www.nabble.com/Convert-dataframe-to-table-with-counts-where-column-names-become-row-names-tp24850797p24850797.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> 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.
>


-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O

	[[alternative HTML version deleted]]

On Aug 6, 2009, at 1:14 PM, ghinkle wrote:
>
> Can anyone explain how best to go from a dataframe to a table (or  
> better yet
> a new dataframe) of counts, where the row names in the new table (or
> dataframe) are the column names of the original df.
>
> start w/
> DF1 >           Pos1  Pos2 Pos3 ....
> oligo1   G       C     A
> oligo2   U       U     A
> oligo3   G       C     C
> oligo4   C       G     U
> oligo5   A       A     G
> .....
 > apply(DF1, 2, table)
   Pos1 Pos2 Pos3
A    1    1    2
C    1    2    1
G    2    1    1
U    1    1    1


Since tables are really matrices, the t() operation would bring you to  
your goal:

 > t( apply(DF1, 2, table) )
      A C G U
Pos1 1 1 2 1
Pos2 1 2 1 1
Pos3 2 1 1 1

>
> End with
>
> DF2 >           G  A  U C
> Pos1   2   1 1 1
> Pos2   1  1  1  2
> Pos3  1  2  1  1
> ....
>
> I know how to generate the counts of each one column at a time using
> "table(DF1$Pos1)".
> Is there a way to do this in one step?  Should I just write a for  
> loop for
> each of the columns?
---

David Winsemius, MD
Heritage Laboratories
West Hartford, CT