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

From: Don MacQueen <macq_at_llnl.gov>
Date: Thu, 27 Mar 2008 08:34:50 -0700

As Gabor said, your zeit should be a POSIXct object, not a POSIXlt object.

Then, for example:

   zeit <- Sys.time() + 1500000*runif(10)    val <- rnorm(10)
   plot(zeit,val,xaxt='n')
   axis.POSIXct(1,zeit, format='%Y-%m-%d %H:%M')

Or better (perhaps) yet:

   plot(zeit,val,xaxt='n')
   axis.POSIXct(1,zeit, format='%Y-%m-%d\n%H:%M', mgp=c(3,2,0))

However, depending on the overall time range, this example might make more sense:

   zeit <- Sys.time() + 15000*runif(10)
   plot(zeit,val,xaxt='n')
   axis.POSIXct(1,zeit, format='%Y-%m-%d\n%H:%M', mgp=c(3,2,0))

> class(zeit)

[1] "POSIXt" "POSIXct"

-Don

At 2:59 PM +0100 3/27/08, erkan yanar 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
>
>______________________________________________
>R-help_at_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.

-- 
--------------------------------------
Don MacQueen
Environmental Protection Department
Lawrence Livermore National Laboratory
Livermore, CA, USA
925-423-1062

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Received on Thu 27 Mar 2008 - 19:39:13 GMT

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