[R] plot POSIXct format data

[Jingru Dai]

Hi, Gabor

It works now, thanks.  The tricky part is I imported my data from Excel 
and converted the data into POSIXct format using command strptime().
So I thought they were already converted into dates and times class.  I 
added as.POSIct, now it works alright.

Thanks for that



Gabor Grothendieck wrote:
> 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
>> ----
>> School of Mathematical Sciences
>> Rm 454, Building 28
>> Monash University, 3800
>> Victoria, Australia
>>
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