R help - Aug 2010 - Best way to Convert String to Time for comparison?

Hi guys,

I have a large text file with a bunch of Time in "HH:MM" format, what
would
be the best way to process it into a Time Object so that I can use
comparisons like (1:00<"1:15") or (13:00>"2:00") to
both return true.

Right now if I do a comparison like (3:00 < "1:59") I get a true,
but if I
do (3:00 < "2:00") I get false, which is an obvious error.


Thanks,
Allan

 
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On Wed, Aug 4, 2010 at 8:43 AM, allany <allany at cmu.edu>
wrote:
>
> Hi guys,
>
> I have a large text file with a bunch of Time in "HH:MM" format,
what would
> be the best way to process it into a Time Object so that I can use
> comparisons like (1:00<"1:15") or (13:00>"2:00")
to both return true.
>
> Right now if I do a comparison like (3:00 < "1:59") I get a
true, but if I
> do (3:00 < "2:00") I get false, which is an obvious error.
>
>
Try this:

library(chron)
t1 <- times(paste("13:00", "00", sep = ":"))
t2 <- times(paste("2:00", "00", sep = ":"))
t1 > t2

Another way is

t1<-  c("3:00","1:59","3:00","2:00")
t2 <- strptime(t1, format="%H:%M")
t2[-4]>t2[-1]


Nikhil Kaza
Asst. Professor,
City and Regional Planning
University of North Carolina

nikhil.list at gmail.com

On Aug 4, 2010, at 8:47 AM, Gabor Grothendieck wrote:
> On Wed, Aug 4, 2010 at 8:43 AM, allany <allany at cmu.edu> wrote:
>>
>> Hi guys,
>>
>> I have a large text file with a bunch of Time in "HH:MM"
format,
>> what would
>> be the best way to process it into a Time Object so that I can use
>> comparisons like (1:00<"1:15") or
(13:00>"2:00") to both return true.
>>
>> Right now if I do a comparison like (3:00 < "1:59") I get
a true,
>> but if I
>> do (3:00 < "2:00") I get false, which is an obvious error.
>>
>>
>
> Try this:
>
> library(chron)
> t1 <- times(paste("13:00", "00", sep =
":"))
> t2 <- times(paste("2:00", "00", sep =
":"))
> t1 > t2
>
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