[R] Mystified - comparing chron times
dwinsemius at comcast.net
Fri Sep 16 16:58:37 CEST 2011
On Sep 16, 2011, at 10:08 AM, B77S wrote:
> I'm sure Sarah's solution works (and she knows more about R than
> myself), but
> I ran into a similar problem and used:
What you did was an implicit rounding of the values to the digits
level specified by some process, possibly a default formatting spec,
guessing to round(num, 7) . I tried to see whether package chron might
specify i,t but this effort only produced this
> cur.opts <- names(options())
Loading required package: chron
> names(options())[!names(options()) %in% cur.opts]
 "chron.year.abb" "chron.year.expand"
What Sarah suggested was essentially rounding to 16 digits to the
right of the decimal.
If the OP had offered dput() on these objects, there would have been
a lot less guessing.
> good luck regardless.
> Sarah Goslee wrote:
>> Sounds like a case for FAQ 7.31, or, yet another machine precision
>> Try all.equal() instead of ==
>> On Fri, Sep 16, 2011 at 7:36 AM, mebstyne <mebstyne at me.com>
>>> I have two local variables: startTime and expectedStartTime. Both
>>> related objects.
>>> When I look at the class for the objects I can see they are of class
>>> When I print them to the console, they both read: "09:30:00"
>>> When I print them as.numeric(), they both read: 0.3958333
>>> When I try and compare them: (as.numeric(startTime) ==
>>> as.numeric(expectedStartTime)) it returns FALSE.
>>> I'm mystified. I would expect them to be true.
>>> Perhaps a key to the riddle is how the two objects were created.
>>> "startTime" was created by reading a text field from a socket,
>>> into a chron object using chron(x, "%m/$d/%Y %H:%M:%S"), then
>>> finally I
>>> created a time out of the chron by doing a quick butchering of the
>>> portion of the numeric: (times(as.numeric(x) - as.integer(x))
>>> "expectedStartTime" was created by the command times('09:30:00')
>>> Any suggestions? Tips? Alternative approaches? I've pulled too
>>> triaging this.
>>> All hands welcomed on this little challenge.
>>> Big picture goal of what I'm doing: I have a list of chron objects
>>> dates and times portion filled out and I'm trying to determine if
>>> is a specific time (specific to the minute).
>> Sarah Goslee
>> R-help at r-project.org mailing list
>> PLEASE do read the posting guide
>> and provide commented, minimal, self-contained, reproducible code.
> View this message in context: http://r.789695.n4.nabble.com/Mystified-comparing-chron-times-tp3817855p3818176.html
> Sent from the R help mailing list archive at Nabble.com.
> R-help at r-project.org mailing list
> 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
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