[R] Plot with x-axis dates
murdoch at stats.uwo.ca
Sat Feb 7 12:10:12 CET 2009
On 06/02/2009 4:48 PM, Paul Warren Simonin wrote:
> I am attempting to create plots using two continuous variables and
> it seems I should be able to use the simple "plot" command. However,
> my x-axis values are dates, and I believe this could be the reason I
> am receiving error messages reading:
> Error in Summary.factor(c(2L, 4L, 3L, 5L, 6L, 7L, 1L), na.rm = FALSE) :
> range not meaningful for factors
> I have attempted to convert the date values to official dates within R
> and have done that successfully using the as.date function, but this
> did not help in the plots. So, how can one create plots in which the
> x-axis is date values? I know it would be possible to convert all my
> dates into a different linear scale (e.g., julian dates). However, I
> would like to complete this process as simply as possible.
You can do plots using dates on the axis, e.g.
dates <- ISOdate(2009, 1:12, 1) # first of every month
Now sometimes the default tick choices for dates don't look great, e.g.
only gets two ticks labelled Jan and Mar, but you can specify your own
locations and labels:
plot(dates[1:3], 1:3, xaxt="n")
axis(1, at=dates[1:3], labels=format(dates[1:3], "%b %d"))
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