[R] Pb with date time sequence with period<1sec

[Sarah Goslee]

Looks like R FAQ 7.31 to me.

https://cran.r-project.org/doc/FAQ/R-FAQ.html#Why-doesn_0027t-R-think-these-numbers-are-equal_003f

On Wed, Sep 9, 2015 at 4:19 AM, DE <david.ecotiere at cerema.fr> wrote:
> Hi,
>
> I'd like to create a date-time seq with a period of 0.05 s, over several
> days.
>
> # try :
> start<-strptime(nom_fich,format="%y%m%d")
> time<-seq(from=start, by=0.05, length.out = 86400*20*3)
> print(as.POSIXlt(time[2])$sec)
> # result is 0.04999995 and not 0.05 as expected
>
> But If I am looking at the sequence, the seconds are not separated by 0.05,
> but by something very close (0.04999995). Same pb if I want to add a
> fraction of seconds to a date-time object :
>
> # try :
> start<-strptime(nom_fich,format="%y%m%d")
> as.POSIXlt(start+0.05,origin="1970-01-01")$sec
> # result is 0.04999995 and not 0.05 as expected
>
> Any idea to solve this pb ?
>
> Thank you in advance !
>
>


-- 
Sarah Goslee
http://www.functionaldiversity.org