R help - Oct 2010 - (no subject)

Dear List,

I am trying to plot date vs. time, but am having problems getting my y-axis 
labels how I want them.? When left on its own R plots time at 6 hour intervals 
from 03:00 to 23:00.? I am wanting 6 hour intervals from 2:00 to 22:00.? I 
realize yaxp doesn't work in plot(), so I am trying to get it to work in
par().?
However, now I get the ticks where I want them but the time is output as a very 
big number (serial time?).? I have also tried axis() using at= and also get 
seriel time numbers.? Any suggestions on how to format time on an axis?

? mydat$Date<-as.POSIXct(as.character(mydat$Date),
format=c("%m/%d/%Y"))
? mydat$Time<-as.POSIXct(as.character(mydat$Time),
format=c("%H:%M:%S"))

? plot(mydat$DateTime,mydat$Time, xlab=c("Date"),
ylab=c("Time"),
? xlim=c(min(mydat$DateTime),max(mydat$DateTime)),
? ylim=c(min(mydat$Time),max(mydat$Time)),
? yaxt="n",
? yaxs="i",
? pch=19, cex=.4,
? type="n")

? par(yaxp=c(as.POSIXct(as.character("02:00"), 
format=c("%H:%M")),as.POSIXct(as.character("22:00"),
format=c("%H:%M")),5))
? axis(2)


Thanks,

Tim
?Tim Clark

Marine Ecologist
National Park of American Samoa

Two  things I see. First is that par needs to be called _before_ the  
plot (although its effects will persist if you need to keep hacking  
away)  and the second is that yaxp is expecting numeric arguments  
(which you are offering)  but in your case these will need to be the  
numeric values in a Date-aligned version of those DateTimes used in  
your mydat arguments. POSIXct is the number of seconds since the origin.

-- 
David.

On Oct 11, 2010, at 6:56 PM, Tim Clark wrote:
> Dear List,
>
> I am trying to plot date vs. time, but am having problems getting my  
> y-axis
> labels how I want them.  When left on its own R plots time at 6 hour  
> intervals
> from 03:00 to 23:00.  I am wanting 6 hour intervals from 2:00 to  
> 22:00.  I
> realize yaxp doesn't work in plot(), so I am trying to get it to  
> work in par().
> However, now I get the ticks where I want them but the time is  
> output as a very
> big number (serial time?).  I have also tried axis() using at= and  
> also get
> seriel time numbers.  Any suggestions on how to format time on an  
> axis?
>
>   mydat$Date<-as.POSIXct(as.character(mydat$Date), format=c("%m/%d/
> %Y"))
>   mydat$Time<-as.POSIXct(as.character(mydat$Time), format=c("%H:%M:
> %S"))
>
>   plot(mydat$DateTime,mydat$Time, xlab=c("Date"),
ylab=c("Time"),
>   xlim=c(min(mydat$DateTime),max(mydat$DateTime)),
>   ylim=c(min(mydat$Time),max(mydat$Time)),
>   yaxt="n",
>   yaxs="i",
>   pch=19, cex=.4,
>   type="n")
>
>   par(yaxp=c(as.POSIXct(as.character("02:00"),
> format=c("%H:%M")),as.POSIXct(as.character("22:00"),
format=c("%H:
> %M")),5))
>   axis(2)
>
>
> Thanks,
>
> Tim
>  Tim Clark
>
> Marine Ecologist
> National Park of American Samoa
>
>
>
>
> ______________________________________________
> 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.
David Winsemius, MD
West Hartford, CT

use 'axis' with 'at=' and 'labels=' to put your own
labels on the axis.

Have to guess at your data since you did not provide a reproducible example:

x <- seq(as.POSIXct('2010-10-11 00:00'), as.POSIXct('2010-10-12
00:00'), length = 20)
plot(x, x, type = 'o', yaxt = 'n')
axis.POSIXct(2, at = seq(as.POSIXct('2010-10-11 02:00'),
as.POSIXct('2010-10-12 00:00'),
    by = '6 hours'))


On Mon, Oct 11, 2010 at 6:56 PM, Tim Clark <mudiver1200 at yahoo.com>
wrote:
> Dear List,
>
> I am trying to plot date vs. time, but am having problems getting my y-axis
> labels how I want them.? When left on its own R plots time at 6 hour
intervals
> from 03:00 to 23:00.? I am wanting 6 hour intervals from 2:00 to 22:00.? I
> realize yaxp doesn't work in plot(), so I am trying to get it to work
in par().
> However, now I get the ticks where I want them but the time is output as a
very
> big number (serial time?).? I have also tried axis() using at= and also get
> seriel time numbers.? Any suggestions on how to format time on an axis?
>
> ? mydat$Date<-as.POSIXct(as.character(mydat$Date),
format=c("%m/%d/%Y"))
> ? mydat$Time<-as.POSIXct(as.character(mydat$Time),
format=c("%H:%M:%S"))
>
> ? plot(mydat$DateTime,mydat$Time, xlab=c("Date"),
ylab=c("Time"),
> ? xlim=c(min(mydat$DateTime),max(mydat$DateTime)),
> ? ylim=c(min(mydat$Time),max(mydat$Time)),
> ? yaxt="n",
> ? yaxs="i",
> ? pch=19, cex=.4,
> ? type="n")
>
> ? par(yaxp=c(as.POSIXct(as.character("02:00"),
> format=c("%H:%M")),as.POSIXct(as.character("22:00"),
format=c("%H:%M")),5))
> ? axis(2)
>
>
> Thanks,
>
> Tim
> ?Tim Clark
>
> Marine Ecologist
> National Park of American Samoa
>
>
>
>
> ______________________________________________
> 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.
>


-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem that you are trying to solve?