[R] Help with Converting Excel Times to R

[Shawn Way]

Thank you very much!  That worked.  I didn't need the unclass(as.Date...) as the as.POSIXlt required me to use an origin to make the transformation.

The working code is as follows:

> times <- c(42935.5625,42935.5694444444)
as.POSIXct((times*86400),origin="1904-01-01",tz="America/Chicago")
[1] "2021-07-20 08:30:00 CDT" "2021-07-20 08:39:59 CDT"


I've never heard of the "1904-01-01" origin, only the "1899-12-30" origin for excel.  Nor did I know about the multiplication of 86400.

Thank you again! 


Shawn Way

-----Original Message-----
From: Jim Lemon <drjimlemon using gmail.com> 
Sent: Wednesday, July 21, 2021 6:09 PM
To: Shawn Way <sway using empowerpharmacy.com>
Cc: r-help using r-project.org
Subject: Re: [R] Help with Converting Excel Times to R

Hi Shawn,
I don't have any trouble with this:

times<-c("7/20/21 13:30","7/20/21 13:40") strptime(times,"%m/%d/%y %H:%M",tz="GMT") [1] "2021-07-20 13:30:00 GMT" "2021-07-20 13:40:00 GMT"

I suspect that Excel is causing the problem. Try changing the format of the date column to "Text" and work on the character representation of the dates.

Jim

On Thu, Jul 22, 2021 at 8:49 AM Shawn Way <sway using empowerpharmacy.com> wrote:
>
> I've usually had good luck with this, but something is not working 
> well.  I have two datetimes in excel
>
> 7/20/21 13:30
> 7/20/21 13:40
>
> And when I convert these to excel's normal storage schema, I get the following:
>
> 42935.5625
> 42935.56944
>
> Just try to convert this to a POSIX class gives me issues.
>
> > dt <- c(42935.5625,42935.5694444444)
>
> > as.POSIXct(dt,origin="1899-12-30 00:00:00",tz="GMT")
>
> [1] "1899-12-30 11:55:36 GMT" "1899-12-30 11:55:36 GMT"
>
> As you can see, there is a world of difference here.  I've tried any 
> number of solutions such as lubridate, etc and I get the same result
>
> > as_datetime(dt,origin="1899-12-30 00:00:00")
>
> [1] "1899-12-30 11:55:36 UTC" "1899-12-30 11:55:36 UTC"
>
> Any ideas about what I'm doing wrong?
>
>
> Shawn Way
>
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