[R] Combine 'overlapping' dataframes, respecting row names

[Prof Brian Ripley]

'merge' is the key here.  You say you want to merge, but it seems did not 
try merge()

> (res <- merge(cvsFrame, downloadsFrame, by="row.names", all=TRUE))
   Row.names cvsactions downloads
1 2002-11-15          4        12
2 2002-12-15          9         8
3 2003-01-15          5        NA
4 2003-02-15          5        NA
5 2002-09-15         NA         1
6 2002-10-15         NA         2

You can sort on Row.names later: say

res[order(as.character(res$Row.names)), ]


On Thu, 31 Aug 2006, James Howison wrote:

> Hi,
> 
> I've examined the archives and found quite a few questions on  
> concatenating dataframes, but none that really addressed my issue,  
> I'm afraid.  I've also examined the cbind and rbind documentation but  
> nonetheless here I am writing to r-help ;)
> 
> This is what I have (the row names are dates used for conversion to  
> an irregular time series with the its package):
> 
>  > cvsFrame
>             cvsactions
> 2002-11-15          4
> 2002-12-15          9
> 2003-01-15          5
> 2003-02-15          5
> 
>  > downloadsFrame
>              downloads
> 2002-09-15          1
> 2002-10-15          2
> 2002-11-15         12
> 2002-12-15          8
> 
> (notice how the dates are overlapping?)
> 
> The output I'd like is:
> 
>             cvsaction  downloads
> 2002-09-15       NA          1
> 2002-10-15       NA          2
> 2002-11-15       4          12
> 2002-12-15       9           8
> 2003-01-15       5          NA
> 2003-02-15       5          NA
> 
> ie. merge the data.frames, respecting the row.names and inserting NAs  
> where a frame didn't contain info for a row in the final frame.
> 
> This is the closest I gotten (I'm sure cbind is doing what it's meant  
> to do but it's obviously not what I need)
> 
>  > cbind(downloadsFrame,cvsFrame)
>              downloads cvsactions
> 2002-09-15          1          4
> 2002-10-15          2          9
> 2002-11-15         12          5
> 2002-12-15          8          5
> 
> It takes the row.names from the first frame given and then just adds  
> the data in rows 1 through 4, regardless of their row.name. And it  
> doesn't work at all if the column lengths are different. (Yes, it  
> would be nice if the 'its' class had a way to merge 'its' objects,  
> but the question seemed general enough to ask on list.)
> 
> Thanks,
> James
> 
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> 

-- 
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