counting frequencies across two columns
On Sun, 01-Nov-2009 at 01:20AM -0500, Jason Priem wrote:
I've got a data frame describing comments on an electronic journal, wherein each row is a unique comment, like so: commentID author articleID 1 1 smith 2 2 2 jones 3 3 3 andrews 2 4 4 jones 1 5 5 johnson 3 6 6 smith 2
Let's call that dataframe x
I want know the number of unique authors per article. I can get a table of article frequencies with table(articleID), but I can't figure out how to count frequencies in a different column. I'm sure there's an easy way, but I guess I'm too new at this to find it.
I'm not clear what you require, but maybe it's this:
with(x, table(articleID, author))
articleID andrews johnson jones smith
1 0 0 1 0
2 1 0 0 2
3 0 1 1 0
Is that anything like what you're after?
~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.
___ Patrick Connolly
{~._.~} Great minds discuss ideas
_( Y )_ Average minds discuss events
(:_~*~_:) Small minds discuss people
(_)-(_) ..... Eleanor Roosevelt
~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.