Lorenzo Isella
2013-Feb-08 20:57 UTC
[R] Merging and Updating Data Frames with Unequal Size
Dear All,
I am trying to merge 2 dataframes of with different sizes.
Let's say that one dataframe R contains some raw data and another data
frame F contains the information to fix R.
For instance
F <- data.frame(cbind(x=-seq(10),
y=1:10,
z=3:12,
w=8:17,
p=18
))
R <- data.frame(cbind(x=rep(-seq(3),5), y=18:32,z=100:86,w=4,k=9))
I would like to do the following: for every value of R$x (i.e. 1,2,3 in
this case), I will look up the same value in
F$x and use the info on that row of F to update the values of R$y, R$z,R$w
(i.e. the raws which have the same names in both data frames), whereas I
will simply append (as a new column) the values of F$p to the new
dataframe.
The resulting data frame should look like this
x y z w k p
-1 1 3 8 9 18
-2 2 4 9 9 18
-3 3 5 10 9 18
-1 1 3 8 9 18
-2 2 4 9 9 18
-3 3 5 10 9 18
-1 1 3 8 9 18
-2 2 4 9 9 18
-3 3 5 10 9 18
-1 1 3 8 9 18
-2 2 4 9 9 18
-3 3 5 10 9 18
-1 1 3 8 9 18
-2 2 4 9 9 18
-3 3 5 10 9 18
(it took longer to explain it than to do it!).
I can do this with a double loop, but I think that playing with the merge
command should do the trick, although so far I have been unsuccessful.
Any suggestion is welcome.
Lorenzo
Hi, Try: ?R[,2:4]<-F[,2:4][match(R$x,F$x),] ?R$p<- unique(F$p) ??? R ??? x y z? w k? p 1? -1 1 3? 8 9 18 2? -2 2 4? 9 9 18 3? -3 3 5 10 9 18 4? -1 1 3? 8 9 18 5? -2 2 4? 9 9 18 6? -3 3 5 10 9 18 7? -1 1 3? 8 9 18 8? -2 2 4? 9 9 18 9? -3 3 5 10 9 18 10 -1 1 3? 8 9 18 11 -2 2 4? 9 9 18 12 -3 3 5 10 9 18 13 -1 1 3? 8 9 18 14 -2 2 4? 9 9 18 15 -3 3 5 10 9 18 A.K. ----- Original Message ----- From: Lorenzo Isella <lorenzo.isella at gmail.com> To: "r-help at stat.math.ethz.ch" <r-help at stat.math.ethz.ch> Cc: Sent: Friday, February 8, 2013 3:57 PM Subject: [R] Merging and Updating Data Frames with Unequal Size Dear All, I am trying to merge 2 dataframes of with different sizes. Let's say that one dataframe R contains some raw data and another data frame F contains the information to fix R. For instance F <- data.frame(cbind(x=-seq(10), ? ? ? ? ? ? ? ? ? ? ? y=1:10, ? ? ? ? ? ? ? ? ? ? ? z=3:12, ? ? ? ? ? ? ? ? ? ? ? w=8:17, ? ? ? ? ? ? ? ? ? ? ? p=18 ? ? ? ? ? ? ? ? ? ? ? )) R <- data.frame(cbind(x=rep(-seq(3),5), y=18:32,z=100:86,w=4,k=9)) I would like to do the following: for every value of R$x (i.e. 1,2,3 in this case), I will look up the same value in F$x and use the info on that row of F to update the values of R$y, R$z,R$w (i.e. the raws which have the same names in both data frames), whereas I will simply append (as a new column) the values of F$p to the new dataframe. The resulting data frame should look like this x y z? w k? p -1 1 3? 8 9 18 -2 2 4? 9 9 18 -3 3 5 10 9 18 -1 1 3? 8 9 18 -2 2 4? 9 9 18 -3 3 5 10 9 18 -1 1 3? 8 9 18 -2 2 4? 9 9 18 -3 3 5 10 9 18 -1 1 3? 8 9 18 -2 2 4? 9 9 18 -3 3 5 10 9 18 -1 1 3? 8 9 18 -2 2 4? 9 9 18 -3 3 5 10 9 18 (it took longer to explain it than to do it!). I can do this with a double loop, but I think that playing with the merge command should do the trick, although so far I have been unsuccessful. Any suggestion is welcome. Lorenzo ______________________________________________ R-help at 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.