Hi Monica, merge(t1, t2) works on your example. So why don't you use merge?
HTH, Thierry ------------------------------------------------------------------------ ---- ir. Thierry Onkelinx Instituut voor natuur- en bosonderzoek / Research Institute for Nature and Forest Cel biometrie, methodologie en kwaliteitszorg / Section biometrics, methodology and quality assurance Gaverstraat 4 9500 Geraardsbergen Belgium tel. + 32 54/436 185 thierry.onkel...@inbo.be www.inbo.be To call in the statistician after the experiment is done may be no more than asking him to perform a post-mortem examination: he may be able to say what the experiment died of. ~ Sir Ronald Aylmer Fisher The plural of anecdote is not data. ~ Roger Brinner The combination of some data and an aching desire for an answer does not ensure that a reasonable answer can be extracted from a given body of data. ~ John Tukey -----Oorspronkelijk bericht----- Van: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] Namens Monica Pisica Verzonden: dinsdag 17 februari 2009 15:33 Aan: R help project Onderwerp: [R] joining "one-to-many" Hello list, I am wondering if a joining "one-to-many" can be done a little bit easier. I tried merge function but I was not able to do it, so I end up using for and if. Suppose you have a table with locations, each location repeated several times, and some attributes at that location. The second table has the same locations, but only once with a different set of attributes. I would like to add the second set of attributes to the first table. Example: set.seed <- 123 loc <- c(rep("L1", 3), rep("L2", 5), rep("L3", 2)) val1 <- round(rnorm(10),2) val2 <- c("a", "b", "c", "a", "b", "d", "f", "e", "b", "e") t1 <- data.frame(loc, val1, val2) t2 <- data.frame(loc=c("L1","L2","L3"), val3 = c("m", "n", "p"), val4 = c(25, 67, 48)) # join one-to-many n <- nrow(t1) m <- nrow(t2) t1$val3 <- rep(1, n) t1$val4 <- rep(1, n) for (i in 1:n) { for (j in 1:m){ if (t1$loc[i]==t2$loc[j]) { t1$val3[i] <- as.character(t2$val3[j]) t1$val4[i] <- t2$val4[j] } } } Desired result: t1 loc val1 val2 val3 val4 1 L1 -0.41 a m 25 2 L1 -0.69 b m 25 3 L1 0.36 c m 25 4 L2 1.11 a n 67 5 L2 0.15 b n 67 6 L2 -0.80 d n 67 7 L2 -0.08 f n 67 8 L2 -1.01 e n 67 9 L3 -1.01 b p 48 10 L3 -2.50 e p 48 This code works OK but it is slow if the data frames are actually bigger than my little example. I hope somebody knows of a better way of doing these type of things. Thanks, Monica _________________________________________________________________ 22009 ______________________________________________ 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. Dit bericht en eventuele bijlagen geven enkel de visie van de schrijver weer en binden het INBO onder geen enkel beding, zolang dit bericht niet bevestigd is door een geldig ondertekend document. The views expressed in this message and any annex are purely those of the writer and may not be regarded as stating an official position of INBO, as long as the message is not confirmed by a duly signed document. ______________________________________________ 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.
