Try this:

Lines <- " protokollid     date        start      end
4 2/23/2009  8:50:10 15:17:30
4 2/24/2009  9:47:00 13:52:25
5 3/22/2009  8:51:25 12:00:05"

library(chron)
skiers <- read.table(textConnection(Lines), header = TRUE, as.is = TRUE)
skiers <- transform(skiers, date = dates(date),
    start = times(start), end = times(end))

bp <- boxplot(as.numeric(skiers$start), yaxt = "n")
axis(2, bp$stats, times(bp$stats), las = 2, cex.axis = 0.5)


On Sat, Dec 5, 2009 at 6:52 AM, uvilla <maruchavez83@hotmail.com> wrote:

>
> hi again
>
> I will try this time to explain my problem clearly
> I have the following data from the file skiing.csv (3 first rows)
>
>  protokollid     date        start      end
> 1            4 2/23/2009  8:50:10 15:17:30
> 2            4 2/24/2009  9:47:00 13:52:25
> 3            5 3/22/2009  8:51:25 12:00:05
>
>
> I have the following script
>
> library(chron)
>
> skiers=read.csv("skiing.csv")
> strptime("08:50:10","%H:%M:%S")
>
> start=times(skiers[,3])
> strptime(start,"%H:%M:%S")
> end=times(skiers[,4])
> strptime(end,"%H:%M:%S")
>
> #calc lenght of the route
> length.route=end-start
>
> #calc medians
> median(start)
> median(length.route)
>
> Then I want to do a box plot of the staring time
> when I use:
>
> boxplot(start)
>
> this error appears: Warning message:
> In is.na(x) : is.na() applied to non-(list or vector) of type 'NULL'
>
> when I try to convert start as POSIXct
>
> > start=as.POSIXct(start)
> Error in as.POSIXct.default(start) :
>  do not know how to convert 'start' to class "POSIXlt"
>
> and when I try to convert skiers[,3] as POSIXct
>
> > skiers[,3]=as.POSIXct(skiers[,3])
> Error in as.POSIXlt.character(as.character(x)) :
>  character string is not in a standard unambiguous format
>
> start is of "times" class and skiers[,3] of "factor" class
>
> I want to do a boxplot of the starting time of my data, which reflect the
> median " 08:36:45", and all O get in the y axis are decimal numbers :(
> Help please
>
> Best regards
>
> Maria Stauss
>
>
> --
> View this message in context:
> http://n4.nabble.com/HELP-boxplot-for-time-class-tp949154p949154.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
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>

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