[R] increase number of ticks on x axis of dates

[David Winsemius]

Ask yourself:

a) whether anyone could possibly see what you are seeing with the data  
you have offered, and ...

(Just a guess that this is the problem)

b) what POSIXct dates are represented by 1:9? Would they even be in  
the range 2001-2009?

 > ddd <- as.POSIXct(strptime(c("01/01/2000", "01/02/2000"),format="%m/ 
%d/%Y"))
 > ddd
[1] "2000-01-01 EST" "2000-01-02 EST"
 > ddd+1
[1] "2000-01-01 00:00:01 EST" "2000-01-02 00:00:01 EST"


On Jun 8, 2009, at 2:59 PM, Graves, Gregory wrote:

> My x axis is a series of daily dates (e.g., 01/01/2000, 01/02/2000,
> etc.) from 2000 to end of 2008.  The default only gives me 4 ticks.  I
> want more.  Why doesn't this work?
>
> sdate<-as.POSIXct(strptime(date,format="%m/%d/%Y"))
>
> plot 
> (ppt~sdate,type="l",ylim=c(0,47),col=1,lwd=1,pch=16,ylab="Salinity,
> psu",xlab="Year",las=1,main="Duck Key Salinity",xaxt="n")
>
> year.text=c("2001","2002","2003","2004", "2005", "2006",  
> "2007","2008",
> "2009")
>
> axis(1, at=c(1:9),labels=year.text)
>

David Winsemius, MD
Heritage Laboratories
West Hartford, CT