Dear useRs,
I'm struggling again with date-related stuff: I am using R to draw water levels
at certain measuring
stations. My data comes as a tab-delimited text file and looks like this:
DATUM P1 P2
...
2006-11-16 425.21 423.99
2006-12-15 425.12 423.97
2007-01-16 425.16 424.06
...
(measurements started in July 2004 and still continue on a monthly or bi-weekly
basis)
This is then plotted using this code:
a<-read.table("dummy_data.tab", sep="\t", header=TRUE, na.strings=c(0))
x<-as.Date(a$DATUM)
plot(x, a$P1, axes=FALSE, xlim=c(as.Date("2004-07-01"), as.Date("2009-01-01")),
ylim=c(423,428), col="red", pch=15, type="o", ylab="Kote [m a.s.l.]",
main="Dummy Plot")
points(x, a$P2, col="red", pch=17, type="o", lty="dotted")
axis(2, at=423:428, tck=1, col="gray60")
axis.Date(1, at=seq(as.Date("2004-07-01"), as.Date("2009-01-01"),
by="month"), labels=seq(as.Date("2004-07-01"), as.Date("2009-01-01"),
by="month"), tck=1, col="gray60")
So far, I've been using this type of date format (yyyy-mm-dd) because that was
the only way I could
get the whole thing to work when I started using R. However, living in
Switzerland, I would prefer
the dates to read 16.11.2006 i.e. dd.mm.yyyy or 16. Nov. 2006 (preferably using
German names for
the months, if possible).
I've used the chron package to convert my dates to day mon year (16 Nov 2006,
with or without
spaces), i.e. I replaced the second line of code with:
x<-format(chron(as.character(a$DATUM), format="y-m-d", out.format="day mon
year"))
but then I can't plot them any more, because as.Date() no longer is the correct
function and R gives
me an error saying there is an invalid xlim-value. Can someone please point me
in the right
direction?
I could easily change the input data to be in dd.mm.yyyy format, if that helps.
Thanks for your help,
Kathi
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