Is because the category is not unique, then merge are replicate the values.
Try this example: x <- data.frame(category=1:10, rnorm(10)) y <- data.frame(category=3:12, rnorm(10)) merge(x, y, by = "category") merge(x, y, by="category", all = T) On Wed, Jun 17, 2009 at 10:04 PM, Martin Batholdy <batho...@googlemail.com>wrote: > I have tried to replicate the example on the help page; > > > x <- data.frame(category = sample(3, 10, r=TRUE), rnorm(10, 5, 2)) > y <- data.frame(category = sample(3, 10, r=TRUE), rnorm(10, 8, 2)) > > merge(x, y, by = "category") > > > > When I do that, I get a data.frame with 28 rows instead of 10. > > What am I doing wrong? > > > > Am 18.06.2009 um 02:42 schrieb David Winsemius: > > > Red the help page for merge: >> >> ?merge >> >> >> On Jun 17, 2009, at 8:33 PM, Martin Batholdy wrote: >> >> hi, >>> >>> >>> I have two data.frames each with two columns; >>> >>> >>> x1 >>> >>> 1 4 >>> 1 3 >>> 1 6 >>> 2 9 >>> 2 2 >>> 2 5 >>> 3 6 >>> 3 7 >>> 3 4 >>> >>> >>> x2 >>> >>> 1 -3 >>> 1 -7 >>> 2 -3 >>> 2 -2 >>> 2 -8 >>> 3 -1 >>> 3 -2 >>> 3 -1 >>> >>> now I want to merge this data.frames to one data.frame. >>> >>> The problem is, that sometimes there is a different number of elements >>> per category. >>> (like above x1 has 3 values for the value 1 in the first row, but x2 has >>> only 2 values for the value 1 in the first row). >>> >>> Is there an easy way to merge this two data.frames by deleting the rows >>> that only one data.frame "has". >>> In the example, that resulting data.frame would be the data.frame x1 and >>> x2 except the row 3 of data.frame x1. >>> >>> thanks for any suggestions! >>> >>> ______________________________________________ >>> 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. >>> >> >> David Winsemius, MD >> Heritage Laboratories >> West Hartford, CT >> >> > ______________________________________________ > 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. > -- Henrique Dallazuanna Curitiba-Paraná-Brasil 25° 25' 40" S 49° 16' 22" O [[alternative HTML version deleted]]
______________________________________________ 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.
