Hi:
On Thu, May 27, 2010 at 10:26 PM, Kang Min <ngokang...@gmail.com> wrote:
> Hi,
>
> I have 2 dataframes of unequal length, and I would like to match a
> factor to them so that both dataframes will have the same number of
> rows.
>
> example:
> # create the 2 dataframes with unequal length
> data1 <- data.frame(letters, 1:26)[-c(5,10,19:21),]
> data2 <- data.frame(letters, 1:26)[-c(6,9,15:18),]
>
If this is your real problem, then an easy thing to do is
data1 <- data2 <- data.frame(letters[1:26])
data1[c(5,10,19:21), ] <- NA
data2[c(6, 9, 15:18), ] <- NA
data3 <- cbind(data1, data2)
names(data3, c('lett1', 'lett2'))
data3
However, I suspect this is not your real problem, so let's add a variable to
each of the data frames you posted and try again:
data1 <- data.frame(letters, 1:26)[-c(5,10,19:21),]
data2 <- data.frame(letters, 1:26)[-c(6,9,15:18),]
data1$x <- rpois(nrow(data1), 10)
data2$y <- rpois(nrow(data2), 5)
# Now merge data1 and data2:
(data3 <- merge(data1, data2, all = TRUE))
letters X1.26 x y
1 a 1 7 1
2 b 2 13 3
3 c 3 10 5
4 d 4 4 9
5 e 5 NA 4
6 f 6 10 NA
7 g 7 15 4
8 h 8 10 6
9 i 9 12 NA
10 j 10 NA 3
11 k 11 8 6
12 l 12 12 3
13 m 13 10 3
14 n 14 7 8
15 o 15 6 NA
16 p 16 8 NA
17 q 17 6 NA
18 r 18 4 NA
19 s 19 NA 2
20 t 20 NA 6
21 u 21 NA 4
22 v 22 12 6
23 w 23 10 3
24 x 24 7 8
25 y 25 9 6
26 z 26 15 7
To get rid of the second column, set data3[, 2] <- NULL.
HTH,
Dennis
> data2a <- match(data1[,1], data2[,1])
> data2b <- data2[data2a,]
>
> When I match data1 to data2, and combine the data2a vector to the
> original data2, I'm still missing some rows. I need to get the 26
> rows, and preferably with the first column displaying all the levels.
> In data2b the mismatches show up as NA in the whole row.
>
> Thanks.
> Kang Min
>
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