Alexander Shenkin
2012-Aug-24 13:47 UTC
[R] POSIXct-coerced NA's not considered NA by is.na()
Hello folks, I found a strangeness while experimenting with POSIXct vectors and lists. It seems that coerced NA's aren't "real" NAs, at least as considered by is.na()?> date_vec = c(as.POSIXct(now()), as.POSIXct(now()+1),NA,"b") > date_vec[1] "2012-08-22 15:00:46 COT" "2012-08-22 15:00:47 COT" NA [4] NA Warning message: In as.POSIXlt.POSIXct(x, tz) : NAs introduced by coercion> date_vec[4][1] NA Warning message: In as.POSIXlt.POSIXct(x, tz) : NAs introduced by coercion> is.na(date_vec[4])[1] FALSE> is.na(date_vec[3])[1] TRUE> is.POSIXct(date_vec[4])[1] TRUE
I think your first problem is the coersion done by 'c' when you are mixing objects of various types: you have POSIXct and character. What were your expections?> x <- Sys.time() > str(x)POSIXct[1:1], format: "2012-08-24 13:12:31"> y <- c(x, 'b') > str(y)POSIXct[1:2], format: "2012-08-24 13:12:31" NA Warning message: In as.POSIXlt.POSIXct(x, tz) : NAs introduced by coercion> dput(y)structure(c("1345828351.75", "b"), class = c("POSIXct", "POSIXt" ))>Look at the 'dput' and see that what it is trying to do is to use the numeric value changed to a character string as a POSIXct value. So I am not surprised by the error since it is probably not what you wanted. Did you intend to use 'list' instead of 'c'? On Fri, Aug 24, 2012 at 9:47 AM, Alexander Shenkin <ashenkin at ufl.edu> wrote:> Hello folks, > > I found a strangeness while experimenting with POSIXct vectors and > lists. It seems that coerced NA's aren't "real" NAs, at least as > considered by is.na()? > >> date_vec = c(as.POSIXct(now()), as.POSIXct(now()+1),NA,"b") >> date_vec > [1] "2012-08-22 15:00:46 COT" "2012-08-22 15:00:47 COT" NA > > [4] NA > Warning message: > In as.POSIXlt.POSIXct(x, tz) : NAs introduced by coercion >> date_vec[4] > [1] NA > Warning message: > In as.POSIXlt.POSIXct(x, tz) : NAs introduced by coercion >> is.na(date_vec[4]) > [1] FALSE >> is.na(date_vec[3]) > [1] TRUE >> is.POSIXct(date_vec[4]) > [1] TRUE > > ______________________________________________ > R-help at 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.-- Jim Holtman Data Munger Guru What is the problem that you are trying to solve? Tell me what you want to do, not how you want to do it.