matrix() does not preserve class attributes, as it merely creates a matrix of mode the mode of its argument (possibly after some coercion), which is "numeric" for POSIXct, as you know.
So why not just manually set the class attribute after creation of the data.frame: mydf <- data.frame(matrix(mydata,ncol=2)) for(i in seq(mydf))class(mydf[[i]]) <- class(mydata) Cheers, Bert Gunter Genentech -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Thomas Pujol Sent: Thursday, January 03, 2008 9:02 AM To: [EMAIL PROTECTED] Subject: [R] retaining formatting when converting a vector to amatrix/data.frame? Please see example code below. I have a vector ("mydata") of length 10. "mydata" can have various formats (e.g. numeric, text, POSIXct, etc) I use the matrix and data.frame functions to convert "mydata" to a dataframe ("mydf") of 2 columns and 5 rows. What is a "good" way to ensure that the format is retained when I create the data.frame? Currently, data in the "POSIXct" format is converted to numeric. Also, for my edification, is there a "good" way to convert numeric values such as these back to the original "POSIXct" format/values? Much thanks! #here I lose the "POSIXct" formatting mydata <- rep(Sys.time(), 10) str(mydata) mydf <- data.frame(matrix(data=mydata, nrow=5, ncol=2)) str(mydf) #here using only "matrix" I also lose the "POSIXct" formatting mydata <- rep(Sys.time(), 10) str(mydata) mydf <- matrix(data=mydata, nrow=5, ncol=2) str(mydf) #this works as intended mydata <- rep(1:10) str(mydata) mydf <- data.frame(matrix(data=mydata, nrow=5, ncol=2)) str(mydf) --------------------------------- [[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. ______________________________________________ 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.
