I guess it is due to vectorization. vec1<- as.Date(Data[,2],origin="1899-12-30") class(vec1) #[1] "Date" as.vector(vec1) # [1] 15758 15765 15772 15779 NA 15793 15800 15807 NA 15821 15828
head(as.list(vec1),2) #[[1]] #[1] "2013-02-22" # #[[2]] #[1] "2013-03-01" head(data.frame(vec1),2) # vec1 #1 2013-02-22 #2 2013-03-01 unlist(as.list(vec1)) # [1] 15758 15765 15772 15779 NA 15793 15800 15807 NA 15821 15828 Also, please check: http://r.789695.n4.nabble.com/as-vector-with-mode-quot-list-quot-and-POSIXct-td4667533.html A.K. ----- Original Message ----- From: Denis Chabot <chabot.de...@gmail.com> To: arun <smartpink...@yahoo.com> Cc: R help <r-help@r-project.org> Sent: Thursday, May 23, 2013 10:06 PM Subject: Re: [R] subsetting and Dates Thank you for the 2 methods to make the columns class Date, but I would really like to know why these variables were not in Date class with my code. Do you know? Denis Le 2013-05-23 à 21:44, arun <smartpink...@yahoo.com> a écrit : > You could convert those columns to "Date" class by: > > > Data[,c(4,6)]<-lapply(Data[,c(4,6)],as.Date,origin="1970-01-01") > #or > Data[,c(4,6)]<-lapply(Data[,c(4,6)],function(x) structure(x,class="Date")) > > > # dat1 dat2 Dat1a Dat1b Dat2a Dat2b > #1 41327 41327 2013-02-22 2013-02-22 2013-02-22 2013-02-22 > #2 41334 41334 2013-03-01 2013-03-01 2013-03-01 2013-03-01 > #3 41341 41341 2013-03-08 2013-03-08 2013-03-08 2013-03-08 > #4 41348 41348 2013-03-15 2013-03-15 2013-03-15 2013-03-15 > #5 41355 NA 2013-03-22 2013-03-22 <NA> <NA> > #6 41362 41362 2013-03-29 2013-03-29 2013-03-29 2013-03-29 > #7 41369 41369 2013-04-05 2013-04-05 2013-04-05 2013-04-05 > #8 41376 41376 2013-04-12 2013-04-12 2013-04-12 2013-04-12 > #9 41383 NA 2013-04-19 2013-04-19 <NA> <NA> > #10 41390 41390 2013-04-26 2013-04-26 2013-04-26 2013-04-26 > #11 41397 41397 2013-05-03 2013-05-03 2013-05-03 2013-05-03 > A.K. > > ----- Original Message ----- > From: Denis Chabot <chabot.de...@gmail.com> > To: R-help@r-project.org > Cc: > Sent: Thursday, May 23, 2013 5:35 PM > Subject: [R] subsetting and Dates > > Hi, > > I am trying to understand why creating Date variables does not work if I > subset to avoid NAs. > > I had problems creating these Date variables in my code and I thought that > the presence of NAs was the cause. So I used a condition to avoid NAs. > > It turns out that NAs are not a problem and I do not need to subset, but I'd > like to understand why subsetting causes the problem. > The strange numbers I start with are what I get when I read an Excel sheet > with the function read.xls() from package gdata. > > dat1 = c(41327, 41334, 41341, 41348, 41355, 41362, 41369, 41376, 41383, > 41390, 41397) > dat2 = dat1 > dat2[c(5,9)]=NA > Data = data.frame(dat1,dat2) > > keep1 = !is.na(Data$dat1) > keep2 = !is.na(Data$dat2) > > > Data$Dat1a = as.Date(Data[,"dat1"], origin="1899-12-30") > Data$Dat1b[keep1] = as.Date(Data[keep1,"dat1"], origin="1899-12-30") > Data$Dat2a = as.Date(Data[,"dat2"], origin="1899-12-30") > Data$Dat2b[keep2] = as.Date(Data[keep2,"dat2"], origin="1899-12-30") > > Data > dat1 dat2 Dat1a Dat1b Dat2a Dat2b > 1 41327 41327 2013-02-22 15758 2013-02-22 15758 > 2 41334 41334 2013-03-01 15765 2013-03-01 15765 > 3 41341 41341 2013-03-08 15772 2013-03-08 15772 > 4 41348 41348 2013-03-15 15779 2013-03-15 15779 > 5 41355 NA 2013-03-22 15786 <NA> NA > 6 41362 41362 2013-03-29 15793 2013-03-29 15793 > 7 41369 41369 2013-04-05 15800 2013-04-05 15800 > 8 41376 41376 2013-04-12 15807 2013-04-12 15807 > 9 41383 NA 2013-04-19 15814 <NA> NA > 10 41390 41390 2013-04-26 15821 2013-04-26 15821 > 11 41397 41397 2013-05-03 15828 2013-05-03 15828 > > So variables Dat1b and Dat2b are not converted to Date class. > > > sessionInfo() > R version 2.15.2 (2012-10-26) > Platform: x86_64-apple-darwin9.8.0/x86_64 (64-bit) > > locale: > [1] fr_CA.UTF-8/fr_CA.UTF-8/fr_CA.UTF-8/C/fr_CA.UTF-8/fr_CA.UTF-8 > > attached base packages: > [1] stats graphics grDevices utils datasets methods base > > other attached packages: > [1] gdata_2.12.0 > > loaded via a namespace (and not attached): > [1] gtools_2.7.0 > > Thanks in advance, > > Denis > ______________________________________________ > 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.
