[R] strptime and plot(),lines()

Gabor Grothendieck ggrothendieck at gmail.com
Thu Mar 27 15:42:10 CET 2008


You normally want to represent your times as POSIXct rather than
POSIXlt so try

xct <- as.POSIXct(xlt)

or you may want to use chron.  Read read more about this in
R News 4/1 which has info on dates and times.

Use the axis or Axis command to create custom axes.
?axis
?Axis

You may also want to look at the zoo package which has numerous
examples of working with and plotting time series including three
vignettes.

On Thu, Mar 27, 2008 at 9:59 AM, erkan yanar <erkan.yanar at linsenraum.de> wrote:
>
> Hello,
>
> Im reading Data out of a Database.
> #v+
> rs <- dbGetQuery(con,"SELECT * ... )
> attach(rs)
> #v-
>
> There ist a colum I convert into "Time".
>
> #v+
> > zeit<-strptime(datum,format="%Y-%m-%d %H:%M:%S");
> > class(zeit)
> [1] "POSIXt"  "POSIXlt"
> #v-
>
> 1.
> A plot(zeit,money) plots the Data.
> All i see on the x-achis are the Days.
> I would like to see the hours also.
>
> 2.
> length(zeit) gives mit the length of one entry.
> But zeit exists of 500 entries.
> How can i get the amount of entries zeit got?
>
> 3.
> Im used to draw whith lines() into an existing plot.
> But something like lines(zeit,food) wouldnt work.
>
> All this works quit well, when Im using unixtime. But seconds  since
> 1970 are not that nice on the x-achis:-)
>
>
>
> Regards
> Erkan Yanar
>
>
>
> --
> über den grenzen muß die freiheit wohl wolkenlos sein
>
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