[R] plot with dates
Halldor Björnsson
halldor at vedur.is
Tue Dec 14 16:01:17 CET 2004
Hi,
I am trying to understand the behaviour of the plot function.
If I have
novdate <- as.Date("2001/11/1") + (0:29)
y <- 1:30
b <- data.frame(novdate,y)
then plot(b$novdate,b$y) will produce a plot where the x-ticmarks are
given as dates (Nov 04, Nov 09 etc), but plot(b) will produce a plot
where the x-tickmars are integer values (#day since Jan 1st 1970)
In the first case plot is getting a an x-vector of class Date, and
y-vector of class integer. In the second case plot gets an object of
class data.frame (but with components of class Date and integer).
I am new to R so I may be wrong about this, but it seems to me that
different plotting methods are invoked. methods(plot) yields a list of
plot methods, but I cannot access most of them.
Is there a way to guide plot(b) to using the method used by
plot(b$novdate,b$y), - or is that a bad idea?...
Sincerely,
HalldÃ³r
------------------------------------------
Halldor Bjornsson (halldor at vedur.is)
Vedurstofa Islands (Icelandic Met. Office)
Bustadavegur 9, IS-150, Reykjavik, Iceland
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