[R] Chron object in time series plot

[David Winsemius]

On Oct 19, 2010, at 1:30 PM, Phil Spector wrote:

> The following will create a POSIXlt object using the current date:
>
>> strptime(sprintf('%06d',breaks),'%H%M%S')
> [1] "2010-10-19 07:00:00" "2010-10-19 07:15:00" "2010-10-19 07:30:00"
> [4] "2010-10-19 07:45:00" "2010-10-19 08:00:00" "2010-10-19 08:15:00"
> [7] "2010-10-19 08:30:00" "2010-10-19 08:45:00" "2010-10-19 09:00:00"
>                      . . .
>
> To get just the hours and minutes, you could use
>
>> format(strptime(sprintf('%06d',breaks),'%H%M%S'),'%H:%M')
> [1] "07:00" "07:15" "07:30" "07:45" "08:00" "08:15" "08:30" "08:45"  
> "09:00"
> [10] "09:15" "09:30" "09:45" "10:00" "10:15" "10:30" "10:45" "11:00"  
> "11:15"
>                     . . .
>
> And I'm still not sure I've answered your question.
>
> 					- Phil Spector

> On Tue, 19 Oct 2010, Manta wrote:
>
>>
>> I do not think that importing the time as character will help me,  
>> as I need
>> to perform several operation with them.

Notice that Phil needed to recast these as a character vector with  
sprintf()  before passing the result to strptime. You cannot do any  
(valid) mathematical operations on them such as substraction or  
addition, since they should have no numerical values between 60*60 and  
2*60*60. Furthermore, any plotting of the "numerical" values will  
create illusory gaps. Any operation you do on them needs to first pass  
through a stage that recognizes that they do not possess the necessary  
attributes to be numbers. I think your resistance to making them  
character values in the first place is entirely misguided.

-- 
David.

>> Again, maybe I am not able to
>> express clearly enough. Let's just focus on this series:
>>
>>> breaks
>> [1]  70000  71500  73000  74500  80000  81500  83000  84500  90000   
>> 91500
>> 93000  94500 100000 101500 103000 104500
>> [17] 110000 111500 113000 114500 120000 121500 123000 124500 130000  
>> 131500
>> 133000 134500 140000 141500 143000 144500
>> [33] 150000 151500 153000 154500 160000 161500 163000 164500 170000  
>> 171500
>> 173000 174500 180000 181500 183000 184500
>>
>> I want a simple function that can convert breaks into a treatable  
>> object by
>> 'zoo' as follows:
>>
>> [1] 07:00 07:15 07:30 ....
>> ..
>> [33]...
>> 18:00 18:15 18:30 18:45
>>
>> Is this possible?
>> -- 
>> View this message in context: http://r.789695.n4.nabble.com/Chron-object-in-time-series-plot-tp3002285p3002458.html
>> Sent from the R help mailing list archive at Nabble.com.
>>
>> ______________________________________________
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>> and provide commented, minimal, self-contained, reproducible code.
>>
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

David Winsemius, MD
West Hartford, CT