On Feb 4, 2008 9:49 AM, Peter Dalgaard <[EMAIL PROTECTED]> wrote:
> [EMAIL PROTECTED] wrote:
> > R 2.6.1 on a Thinkpad T60 running up-to-date Gentoo:
> >
> > Despite the documentation, which says:
> >
> > 'strftime' is an alias for 'format.POSIXlt', and 'format.POSIXct'
> > first converts to class '"POSIXlt"' by calling 'as.POSIXlt'. Note
> > that only that conversion depends on the time zone.
> >
> > strftime fails on POSIXct objects:
> >
> >
> I think the author of those lines would point out that they do NOT imply
> that it shouldn't fail.... In fact, why would you expect
> format.POSIXlt(x) to work on anything but POSIXlt objects?
Ah, you are quite right -- I mis-read the documentation.
Thanks --
/Don Allen
>
> -p
>
>
> >> foo <- as.POSIXct(strptime(x='2007-09-22', format='%Y-%m-%d'))
> >> strftime(x=foo, format='%Y-%m-%d')
> >>
> > Error in strftime(x = foo, format = "%Y-%m-%d") : wrong class
> >
> > It's pretty clear why, given the first two lines of the function:
> >
> >> strftime
> >>
> > function (x, format = "", usetz = FALSE, ...)
> > {
> > if (!inherits(x, "POSIXlt"))
> > stop("wrong class")
> > if (format == "") {
> > times <- unlist(unclass(x)[1:3])
> > secs <- x$sec
> > secs <- secs[!is.na(secs)]
> > np <- getOption("digits.secs")
> > if (is.null(np))
> > np <- 0
> > else np <- min(6, np)
> > if (np >= 1) {
> > for (i in (1:np) - 1) if (all(abs(secs - round(secs,
> > i)) < 1e-06)) {
> > np <- i
> > break
> > }
> > }
> > format <- if (all(times[!is.na(times)] == 0))
> > "%Y-%m-%d"
> > else if (np == 0)
> > "%Y-%m-%d %H:%M:%S"
> > else paste("%Y-%m-%d %H:%M:%OS", np, sep = "")
> > }
> > .Internal(format.POSIXlt(x, format, usetz))
> > }
> > <environment: namespace:base>
> >
> >
> > /Don Allen
> >
> > ______________________________________________
> > R-devel@r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-devel
> >
>
>
> --
> O__ ---- Peter Dalgaard Øster Farimagsgade 5, Entr.B
> c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K
> (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
> ~~~~~~~~~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907
>
>
>
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