[R] Summarizing factor data in table?

[Andy Bunn]

The three was a typo, which I regret very much. I don't know why I didn't
think of apply. I was obsessed with doing it as a table.
Thanks for your response,
-Andy

> -----Original Message-----
> From: Tony Plate [mailto:tplate at acm.org]
> Sent: Tuesday, April 26, 2005 2:00 PM
> To: Andy Bunn
> Cc: R-Help
> Subject: Re: [R] Summarizing factor data in table?
>
>
> Do you want to count the number of non-NA divisions and organizations in
> the data for each year (where duplicates are counted as many times as
> they appear)?
>
>  > tapply(!is.na(foo$div), foo$yr, sum)
> 1998 1999 2000
>     0    4    2
>  > tapply(!is.na(foo$org), foo$yr, sum)
> 1998 1999 2000
>     4    4    2
>  >
>
> Or perhaps the number of unique non-NA divisions and organizations in
> the data for each year?
>
>  > tapply(foo$div, foo$yr, function(x) length(na.omit(unique(x))))
> 1998 1999 2000
>     0    4    2
>  > tapply(foo$org, foo$yr, function(x) length(na.omit(unique(x))))
> 1998 1999 2000
>     4    4    2
>  >
>
> (I don't understand where the "3" in your desired output comes from
> though, which maybe indicates I completely misunderstand your request.)
>
> Andy Bunn wrote:
> > I have a very simple query with regard to summarizing the
> number of factors
> > present in a certain snippet of a data frame.
> > Given the following data frame:
> >
> > 	foo <- data.frame(yr = c(rep(1998,4), rep(1999,4),
> rep(2000,2)), div =
> > factor(c(rep(NA,4),"A","B","C","D","A","C")),
> >       	            org = factor(c(1:4,1:4,1,2)))
> >
> > I want to get two new variables. Object ndiv would give the number of
> > divisions by year:
> >      1998 0
> >      1999 3
> >      2000 2
> > Object norgs would give the number of organizations
> >      1998 4
> >      1999 4
> >      2000 2
> > I figure xtabs should be able to do it, but I'm stuck without a
> for loop.
> > Any suggestions? -Andy
> >
> > ______________________________________________
> > R-help at stat.math.ethz.ch mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide!
> http://www.R-project.org/posting-guide.html
> >
>
>