[R] Merge or combine data frames with missing columns

[Mark Heckmann]

thanks for the elegant solution!

It worked out fine in my case, but when I tried to understand what it does I discovered one little issue.

l <- list(data.frame(a=1, b=2), data.frame(a=2, c=3))
do.call(rbind, lapply(l, "[", unique(unlist(sapply(l, names)))))

will not work. Neither the following list.

l <- list(data.frame(a=1, b=2), data.frame(a=2, c=3, d=5))

I am not able to figure out why. Does anyone know what could be done to fix it?

TIA, Mark


-------- Original-Nachricht --------
> Datum: Mon, 29 Dec 2008 16:17:22 -0200
> Von: "Henrique Dallazuanna" <wwwhsd at gmail.com>
> An: "Mark Heckmann" <mark.heckmann at gmx.de>
> CC: r-help at r-project.org
> Betreff: Re: [R] Merge or combine data frames with missing columns

> Try this:
> 
> do.call(rbind, lapply(l, "[", unique(unlist(sapply(l, names)))))
> 
> Where "l" is your list.
> 
> On Mon, Dec 29, 2008 at 12:18 PM, Mark Heckmann
> <mark.heckmann at gmx.de>wrote:
> 
> >
> > Hi R-experts,
> >
> > suppose I have a list with containing data frame elements:
> >
> > [[1]]
> > (Intercept)          y1          y2          y3          y4
> >  -6.64              0.761      0.383      0.775      0.163
> >
> > [[2]]
> > (Intercept)          y2          y3
> > -3.858             0.854      0.834
> >
> > Now I want to put them into ONE dataframe like this:
> >               (Intercept)           y1          y2         y3          
> y4
> >   1           -6.64              0.761      0.383      0.775      0.163
> >   2         -3.858                  NA       0.854      0.834        NA
> >
> > The problem I encounter is that not always all possible columns
> (Intercept,
> >  y1,  y2, y3,  y4) exist or at least have NA entries .
> >
> > I cannot figure out how (e.g. with merge)...
> >
> > TIA, Mark
> >
> >
> > --
> > Mark Heckmann (Dipl. Wirt.-Ing.)
> > phone +49 (0) 421/1614618
> >
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> >
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> > PLEASE do read the posting guide
> > http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
> >
> 
> 
> 
> -- 
> Henrique Dallazuanna
> Curitiba-Paraná-Brasil
> 25° 25' 40" S 49° 16' 22" O

-- 
Mark Heckmann (Dipl. Wirt.-Ing.)
phone +49 (0) 421/1614618