[R] plot time series / dates (basic)

[bogdan romocea]

Thank you for the suggestions. I managed to fix everything except the
first part. 
	dat <- date[(j-1)*points+1):(j*points)]
causes a syntax error. If I do 
	dat <- vector() 
I end up with numbers (which is fine by me - just like SAS dates).
However, after checking a couple of sources I still have no idea how
to format numbers as dates (for plotting/printing). Does anyone have
an example for formatting 12710 (# of days since 1 Jan 1970) as
19-Oct-04 (in the x axis of a plot)?

Regards,
b.


#function to plot a long time series piece by piece
pl <- function(vara, varb, points)
	{
	date <- as.Date(as.character(Date), "%d-%b-%y")
	pr1 <- vector(mode="numeric")
	pr2 <- vector(mode="numeric")
	#dat <- vector()
	dat <- date[(j-1)*points+1):(j*points)]
	for (j in 1:(round(length(Vol)/points)+1)) #number of plots
		{
		for (i in ((j-1)*points+1):(j*points)) 
			{
			pr1[i-points*(j-1)] <- vara[i]
			pr2[i-points*(j-1)] <- varb[i]
			#dat[i-points*(j-1)] <- date[i]
			#dat <- date[i]
			}
		par(mfrow=c(2,1), mai=c(0.4, 0.5, 0.3, 0.1), omi=c(0.2, 0, 0, 0), 
			cex.axis=0.7, cex=1.2, cex.main=0.7, pch="*") 
		plot(dat, pr1, main=deparse(substitute(vara)), type="o")
		#axis.Date(1,dat,format="%b%y") 
		plot(dat, pr2, main=deparse(substitute(varb)), type="o")
		}
	}





--- Prof Brian Ripley <ripley at stats.ox.ac.uk> wrote:

> On Mon, 1 Nov 2004, bogdan romocea wrote:
> 
> > Dear R users,
> > 
> > I'm having a hard time with some very simple things. I have a
> time
> > series where the dates are in the format 7-Oct-04. 
> 
> So why use as.POSIXct for a date, rather than as.Date?
> 
> > I imported the
> > file with read.csv so the date column is a factor. The series is
> > rather long and I want to plot it piece by piece. The function
> below
> > works fine, except that the labels for date are meaningless (ie
> > 9.47e+08 or 1098000000 - apparently the number of seconds since
> > whatever). I don't want to convert the data frame to a ts object
> > because there are missing days and I don't want any
> interpolation.
> > 
> > 1. How do I replace the date labels with something like 'Mar04',
> > instead of 9.47e+08 / 1098000000?
> 
> Just don't convert them to that format.  You set up
> 
> >       dat <- vector()
> 
> which is not a dates object.  If you use standard R indexing, it
> will
> work. If you throw the class away, it will not.  Try
> 
>        dat <- date[(j-1)*points+1):(j*points)]
> 
> etc (no for loop required).
> 
> If you want a different format, see ?axis.Date
> 
> > 2. In the PDF file, the space between the two graphs printed pair
> by
> > pair is fairly large. Can I remove/reduce the area that seems
> > reserved for Title and X label so that, on a page, the space
> between
> > the graph at the top and the one at the bottom is minimized?
> 
> There's a whole chapter on this in `An Introduction to R': have you
> read 
> it?
> 
> > 3. Given the function below, I haven't discovered a way to have
> > "vara" appear as the Title or Y label in graphs.
> > main=as.character(vara) lists all the values of vara (which is a
> > column from the data frame d). So, how can I use the name of a
> vector
> > as title or label in a plot?
> 
> That's almost an FAQ.  Use deparse(substitute(vara))
> 
> > d <- ('data.csv', header = T, sep = ",", quote="", dec=".", 
> > 	fill = T, skip=0)
> > attach(d)
> > #function to plot a long time series piece by piece
> > pl <- function(vara, varb, points)
> > 	{
> > 	date <- as.POSIXct(strptime(as.character(Date), "%d-%b-%y"), tz
> =
> > "GMT")
> > 	pr1 <- vector(mode="numeric")
> > 	pr2 <- vector(mode="numeric")
> > 	dat <- vector()
> > 	for (j in 1:(round(length(Vol)/points)+1)) #number of plots
> > 		{
> > 		for (i in ((j-1)*points+1):(j*points)) 
> > 			{
> > 			pr1[i-points*(j-1)] <- vara[i]
> > 			pr2[i-points*(j-1)] <- varb[i]
> > 			dat[i-points*(j-1)] <- date[i]
> > 			}
> > 		par(mfrow=c(2,1)) 
> > 		plot(dat, pr1, type="b")
> > 		plot(dat, pr2, type="b")
> > 		}
> > 	}
> > 
> > pdf("Rplots.pdf")
> > pl(Vol, atr, 50)
> > dev.off()
> 
> 
> -- 
> Brian D. Ripley,                  ripley at stats.ox.ac.uk
> Professor of Applied Statistics, 
> http://www.stats.ox.ac.uk/~ripley/
> University of Oxford,             Tel:  +44 1865 272861 (self)
> 1 South Parks Road,                     +44 1865 272866 (PA)
> Oxford OX1 3TG, UK                Fax:  +44 1865 272595
> 
> 



		
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