Hi Brian, This is really odd. I keep getting the NA secs answer, only by running these three lines of code in a new session.
> time3=strptime("2009 06 01 00 47 00",format="%Y %m %d %H %M") > time4=strptime("2009 06 01 00 57 00",format="%Y %m %d %H %M") > diff(c(time3,time4)) Time difference of NA secs Here is the information you requested: > dput(time3) structure(list(sec = 0, min = 47L, hour = 0L, mday = 1L, mon = 5L, year = 109L, wday = 1L, yday = 151L, isdst = -1L), .Names = c("sec", "min", "hour", "mday", "mon", "year", "wday", "yday", "isdst" ), class = c("POSIXt", "POSIXlt")) > dput(time4) structure(list(sec = 0, min = 57L, hour = 0L, mday = 1L, mon = 5L, year = 109L, wday = 1L, yday = 151L, isdst = -1L), .Names = c("sec", "min", "hour", "mday", "mon", "year", "wday", "yday", "isdst" ), class = c("POSIXt", "POSIXlt")) > sessionInfo() R version 2.11.0 (2010-04-22) i386-pc-mingw32 locale: [1] LC_COLLATE=Icelandic_Iceland.1252 LC_CTYPE=Icelandic_Iceland.1252 [3] LC_MONETARY=Icelandic_Iceland.1252 LC_NUMERIC=C [5] LC_TIME=Icelandic_Iceland.1252 attached base packages: [1] grDevices datasets splines graphics stats tcltk utils [8] methods base other attached packages: [1] svSocket_0.9-48 TinnR_1.0.3 R2HTML_2.0.0 Hmisc_3.7-0.1 [5] survival_2.35-8 loaded via a namespace (and not attached): [1] cluster_1.12.3 grid_2.11.0 lattice_0.18-5 svMisc_0.9-57 tools_2.11.0 Thanks, Julian [[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.