Hi:
df <- data.frame(x = 1:10, y = rep(0, 10))
dg <- data.frame(x = c(7, 4, 2, 8, 12, 15), y = letters[1:6])
merge(df, dg, by = 'x', all.x = TRUE)
x y.x y.y
1 1 0 <NA>
2 2 0 c
3 3 0 <NA>
4 4 0 b
5 5 0 <NA>
6 6 0 <NA>
7 7 0 a
8 8 0 d
9 9 0 <NA>
10 10 0 <NA>
HTH,
Dennis
On Fri, Sep 17, 2010 at 2:02 PM, Wang, Ying <ying.w...@uth.tmc.edu> wrote:
> Dear R experts,
>
> I'm new to R. It seems to be a simple question but I just can't find a way
> to do it. Please help me.
>
> I have two data sets x and y as shown in the following. I want to compare
> the first two columns in x and y, find the matched ones and assign the
> relative value from column 2 of y to generate the third column of x. Any
> help wil be appreciated. Thanks.
>
> > x
> [,1] [,2]
> [1,] "1" "0"
> [2,] "2" "0"
> [3,] "3" "0"
> [4,] "4" "0"
> [5,] "5" "0"
> [6,] "6" "0"
> [7,] "7" "0"
> [8,] "8" "0"
> [9,] "9" "0"
> [10,] "10" "0"
> > y
> [,1] [,2]
> [1,] "7" "a"
> [2,] "4" "b"
> [3,] "2" "c"
> [4,] "8" "d"
> [5,] "12" "e"
> [6,] "15" "f"
>
> The result I expect is:
> x
> [,1] [,2] [,3]
> [1,] "1" "0" NA
> [2,] "2" "0" "c"
> [3,] "3" "0" NA
> [4,] "4" "0" "b"
> [5,] "5" "0" NA
> [6,] "6" "0" NA
> [7,] "7" "0" "a"
> [8,] "8" "0" "d"
> [9,] "9" "0" NA
> [10,] "10" "0" NA
>
>
> Best,
>
> Ying
>
> ______________________________________________
> R-help@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.
>
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