On Apr 15, 2010, at 2:28 PM, Christian Raschke wrote:
Is there anything that speaks against just applying gsub to the
factor levels if one would like to keep everything as factors (and
not consider true Date classes or character vectors)? I.e:
> x <- c("2000/01/01", "2001/02/01")
> xd <- as.data.frame(x)
> levels(xd$x) <- gsub("/", "-", levels(xd$x))
Nothing. Other than the fact (which is not at all obvious to the new useRs) that it requires knowledge that the string representations are stored within the factor levels and not the factor values, and that operations on factors are often quite puzzling to the uninitiated. If one were to attempt applying a function that takes Date or Datetime arguments to such a "date-like-factor", it is very likely that the initial results would be failures. The OP referred to the strings as a "date value" rather than as a factor level. I doubt that he realized the default operation of as.data.frame().
-- David.
Christian On 04/15/2010 01:08 PM, David Winsemius wrote:On Apr 15, 2010, at 1:51 PM, prem_R wrote:Hi,every one .I have searched the solutions in the forum for replacing my date value which is in a data frame ,01/01/2000 to 01-01-2000 using replacefunction but got the following warning message x<-"2000/01/01" xd<-as.data.frame(x) xd$x<-replace(xd$x,xd$x=="/","-")The replace function does not work with factors, it works with (complete) vectors, not substrings. It's also a real hassle to do such operations on factors, so just use character vectors and try gsub instead:> x<-"2000/01/01" > xd<-as.data.frame(x, stringsAsFactors=FALSE) > xd$x2<-gsub("/","-", xd$x) > xd x x2 1 2000/01/01 2000-01-01Warning message: In `[<-.factor`(`*tmp*`, list, value = "-") : invalid factor level, NAs generatedIs there any other method of doing it? or am i missing something?. pleaselet me know if you need any more information. Thanks. Prem -- View this message in context: http://n4.nabble.com/Replace-with-in-date-tp1911391p1911391.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ 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 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.-- Christian Raschke Department of Economics and ISDS Research Lab (HSRG) Louisiana State University Patrick Taylor Hall, Rm 2128 Baton Rouge, LA 70803 cras...@lsu.edu ______________________________________________ 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 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.
