[R] plot POSIXct format data

[Gabor Grothendieck]

When I try this:

> x <- as.POSIXct(Sys.Date() + 0:9)
> plot(x, x)
> plot(x ~ x)

The first one does give me dates on both axes but the second one gives
numbers on the Y axis.

Note that you can always not print the axis with plot and then do it yourself
with axis or Axis.  This works for me:

> plot(x ~ x, yaxt = "n")
> Axis(x, side = 2)

> R.version.string # Windows Vista
[1] "R version 2.6.1 Patched (2007-12-06 r43610)"

On Jan 14, 2008 6:37 PM, Jingru Dai <jingru.dai at sci.monash.edu.au> wrote:
> Hi, everyone
>
> I've been trying to make a scatter plot of POSIXct format data to see
> the difference between two start time.
> Like X:
> [1] "1995-05-26 19:00:00" "1995-05-27 01:00:00" "1995-05-27 07:00:00"
> [4] "1995-06-29 01:00:00" "1995-06-29 07:00:00" "1995-06-30 13:00:00"
> [7] "1995-06-30 19:00:00" "1995-07-01 01:00:00" "1995-07-01 07:00:00"
> ......
> Y:
> [1] "1995-05-26 19:00:00" "1995-05-27 01:00:00" "1995-05-27 07:00:00"
> [4] "1995-06-29 01:00:00" "1995-06-29 07:00:00" "1995-06-30 13:00:00"
> [7] "1995-06-30 19:00:00" "1995-07-01 01:00:00" "1995-07-01 07:00:00"
> .......
>
> But it seems plot(x,y) doesn't work, y have to be numeric format.  Is
> there any special command for that or I should change the format of the
> data?
> Thanks
>
> Jingru Dai
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> Monash University, 3800
> Victoria, Australia
>
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