[R] Matched pairs with two data frames

[Patrick Connolly]

On Wed, 16-Apr-2008 at 11:58AM +0200, Udo wrote:


|> I only "need" line 1, 6 and 9. To show this,
|> I added "needed" by hand.
|> 
|>    age school out1 out2	     needed
|> 1    1     10  9.5  1.1      yes
|> 2    1     10  9.5  2.0	     no
|> 3    1     10  9.5  3.5	     no
|> 4    1     10  9.5  4.9	     no
|> 5    1     10  2.3  1.1	     no
|> 6    1     10  2.3  2.0	     yes
|> 7    1     10  2.3  3.5	     no
|> 8    1     10  2.3  4.9	     no
|> 9    2     20  3.3  6.5	     yes
|> 10   2     20  4.1  6.5	     no
|> 11   2     20  5.9  6.5	     no
|> 12   3     33   NA  5.2	     no
|> 13   4     11  4.6   NA	     no
|> 
|> >Whatever it is, can't you subset them out?
|> Yes, that´s the problem. To describe what I mean, I added the
|> variable needed by hand. I don´t know how to compute such a
|> variable to subset.
|> 
|> 
|> My final data frame should look like this:
|>     age school out1 out2	nedded
|> 1    1     10  9.5  1.1 	yes
|> 6    1     10  2.3  2.0	        yes
|> 9    2     20  3.3  6.5	        yes


Now that I know what you want, I can see what can work.  Undoubtedly,
there are far more elegant ways of doing it, but this will work.  

  xx <- merge(treat, control)
  out <- xx[1, ] # set up the out dataframe
  for(i in 2:nrow(xx)){
    x.i <- xx[i, ]
    kk <- logical(4)
    for(j in 1:4)
      kk[j] <- x.i[, j]%in%out[, j]
    if(!kk[4]){ # don't add to output if last column value exists
      if(!all(kk[1:3])) # a different combination of first 3 cols
        out <- rbind(out, x.i)
    }   
  }
  out


  age school out1 out2
1   1     10  9.5  1.1
6   1     10  2.3  2.0
9   2     20  3.3  6.5

If you have very large dataframes, you might like to improve on it.


HTH


-- 
~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.   
   ___    Patrick Connolly   
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 _( Y )_  	  	        Middle minds discuss events 
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