[R] Reading time/date string

[Matthew Walker]

Thanks Mark, that was very helpful.  I'm now sooooo close!

Can anyone tell me how to extract the "value" from an instance of a 
"difftime" class?  I can see the value, but how can I place it in a 
dataframe?

 > time_string1 <- "10:17:07 02 Aug 2007"
 > time_string2 <- "13:17:40 02 Aug 2007"
 >
 > time1 <- strptime(time_string1, format="%H:%M:%S %d %b %Y")
 > time2 <- strptime(time_string2, format="%H:%M:%S %d %b %Y")
 >
 > time_delta <- difftime(time2,time1, unit="sec")
 > time_delta
Time difference of 10833 secs     # <--- I'd like this value just here!
 >
 > data.frame(time1, time2, time_delta)
Error in as.data.frame.default(x[[i]], optional = TRUE) :
        cannot coerce class "difftime" into a data.frame



Thanks again,

Matthew


Mark W Kimpel wrote:
> Look at some of these functions...
>
> DateTimeClasses(base)   Date-Time Classes
> as.POSIXct(base)        Date-time Conversion Functions
> cut.POSIXt(base)        Convert a Date or Date-Time Object to a Factor
> format.Date(base)       Date Conversion Functions to and from Character
>
> Mark
> ---
>
> Mark W. Kimpel MD  ** Neuroinformatics ** Dept. of Psychiatry
> Indiana University School of Medicine
>
> 15032 Hunter Court, Westfield, IN  46074
>
> (317) 490-5129 Work, & Mobile & VoiceMail
> (317) 663-0513 Home (no voice mail please)
>
> ******************************************************************
>
> Matthew Walker wrote:
>> Hello everyone,
>>
>> Can anyone tell me what function I should use to read time/date 
>> strings and turn them into a form such that I can easily calculate 
>> the difference of two?  The strings I've got look like "10:17:07 02 
>> Aug 2007".  If I could calculate the number of seconds between them 
>> I'd be very happy!
>>
>> Cheers,
>>
>> Matthew
>>
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>
> .
>