[R] who to rbind of a list of data.frames

Prof Brian Ripley ripley at stats.ox.ac.uk
Tue Aug 12 10:38:50 CEST 2003

> do.call("rbind", LIST)

does exactly

> DF <- rbind(LIST$X1, LIST$X2, LIST$X3, ..., LIST$XN)

See the help on do.call.

Not that rbind.data.frame is `very fast'.  If your data frames are
all of exactly the same type (no coercions needed, factors with the same 
set of levels, ...) it may be faster to create a new data frame of the 
correct size and insert the data frames by indexing.

On Tue, 12 Aug 2003 lutz.thieme at amd.com wrote:

> could anybody give me a hint, who I can use rbind on a list of
> data.frames, please?
> I have a list with a large number of data.frames of the same structure, like:
> LIST	<- list(X1=data.frame(a=1,b=2), X2=data.frame(a=3,b=4), X3=data.frame(a=5,b=6), ...., XN=data.frame(a=i,b=k))
> I would like to bind all data.frames very fast to a single data.frame,
> something like that:
> DF	<- rbind(LIST$X1, LIST$X2, LIST$X3, ..., LIST$XN)
> But for performance (speed) reasons I won't use a loop.

But rbind.data.frame does use a loop ....

> I also couldn't
> find a solution how I could use lapply. One constraint is, that the
> number of data.frames in the list is not determined and can vary from
> one to more than thousand.

Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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