On Fri, 09 Aug 2013, Manta <mantin...@libero.it> writes: > Dear all, > > I have a problem which I'm not to fix. I have the following two series: > > a=structure(c(33242.5196150509, 34905.8434338503, 38490.6957848689, > 38747.0287172129, 38919.1028597142, 39026.3956586941, 38705.5344288997, > 38545.6274379387, 38651.2079354205, 38748.2769580121), index = > structure(c(14029, > 14032, 14033, 14034, 14035, 14036, 14039, 14040, 14041, 14042 > ), class = "Date"), class = "zoo") > > b=structure(c(53337.7643740991, 52210.2079727035, 50235.4480363949, > 50667.1147389469, 50796.5403152116, 51113.5420947436, 51003.3603311344, > 50654.0539778796, 49927.5267060329, 49320.1813921822), index = > structure(c(14029, > 14032, 14033, 14034, 14035, 14036, 14039, 14040, 14041, 14042 > ), class = "Date"), class = "zoo") > > I want to plot them on the same chart, with the x-axis the Date, and the > y-axis the time in format %H:%M. At the moment, the y series is expressed in > seconds from midnight. I am confused with the as.POSIXct conversion. > >> hours(min(rollrep)) > [1] 9 >> minutes(min(rollrep)) > [1] 34 >> seconds(min(rollrep)) > [1] 27 > > however, by doing the following it seems the minimum time is 11:09, which is > not true. > > as.POSIXct(round(min(rollrep)),origin=Sys.Date()) > [1] "2013-08-09 11:09:14 CEST" > > Do you have any advice? Is there a way to plot only the hours and minutes, > without having to go to the Sys.Date? > > Thank you, > Marco
Please provide a *reproducible* example. (What is 'rollrep'? 'Seconds from midnight' may be ambiguous when there was a change to/from summertime or when time zones are relevant.) Perhaps something like this: require("zoo") plot(merge(a, b), plot.type = "single", yaxt = "n") midnight <- ISOdatetime(2013, 1, 1, 0, 0, 0, "GMT") sq <- seq(0, 86400, by = 300) axis(2, at = sq, labels = format(midnight + sq, "%H:%M")) -- Enrico Schumann Lucerne, Switzerland http://enricoschumann.net ______________________________________________ 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.