You seem to be falling prey to a common misconception that "R" is some 
monolithic tool, when in fact it is a herd of cats.

The "by" function, from the "base" package, returns a list of results returned 
by your function. One approach to making a data frame out of that is to use the 
simplify2array function, transpose, and convert to data frame.

However, there are many other ways to aggregate data as well. Packages plyr, 
sqldf, data.table all have strengths and weaknesses, but you must always keep 
in mind that they are contributed packages and you have to refer to the package 
name if you ask here about using functions from them.
---------------------------------------------------------------------------
Jeff Newmiller                        The     .....       .....  Go Live...
DCN:<jdnew...@dcn.davis.ca.us>        Basics: ##.#.       ##.#.  Live Go...
                                      Live:   OO#.. Dead: OO#..  Playing
Research Engineer (Solar/Batteries            O.O#.       #.O#.  with
/Software/Embedded Controllers)               .OO#.       .OO#.  rocks...1k
--------------------------------------------------------------------------- 
Sent from my phone. Please excuse my brevity.

Onur Uncu <onuru...@gmail.com> wrote:
>I used the by() function on a data.frame to get sums of the data
>grouped by 2 factors. The function worked however the output is in a
>class called 'by'. Not familiar with this class. How can I turn the
>output into a nice table where columns represent values of factor1, row
>represent values of factor2 and the entries in the table are the sums
>that were calculated using the by function?
>
>I did some web search which suggested using do.call(rbind,
>datframe_object) but this command gave the following error:
>"Second argument must be a list"...
>
>
>Thank you.
>______________________________________________
>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.

______________________________________________
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.

Reply via email to