[R] by class...

[Onur Uncu]

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.