Thanks, Dennis! I'll go with it. It's surprising there is no ready way to do
that. I imagine it should be a common data manipulation to add two
data.frame from two different sources. It could happen that one data.frame
is missing some rows while the other have some more.

On Fri, Apr 15, 2011 at 5:10 PM, Dennis Murphy <djmuser@gmail.com> wrote:

> Hi:
>
> Here's one approach:
>
> > df1 <- data.frame(x = letters[1:3], y = 1:3)
> > df2 <- data.frame(x = c('a', 'c'), z = c(6, 1))
> > dfm <- merge(df1, df2, all.x = TRUE)
> > dfm
>  x y  z
> 1 a 1  6
> 2 b 2 NA
> 3 c 3  1
> sumdf <- data.frame(x = dfm$x, y = rowSums(dfm[, -1], na.rm = TRUE))
>  x y
> 1 a 7
> 2 b 2
> 3 c 4
>
> HTH,
> Dennis
>
> On Fri, Apr 15, 2011 at 1:31 PM, zhenjiang xu <zhenjiang.xu@gmail.com>
> wrote:
> > Hi all,
> >
> > Suppose I have 2 data.frame , a and b, how can I add them together to get
> c?
> > Thanks
> >> a
> >  A
> > a 1
> > b 2
> > c 3
> >
> >> b
> >  A
> > a 6
> > c 1
> >
> >> c
> >   A
> > a 7
> > b 2
> > c 4
> >
> > --
> > Best,
> > Zhenjiang
> >
> >        [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > 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.
> >
>



-- 
Best,
Zhenjiang

	[[alternative HTML version deleted]]

