[R] difftime in years

[Jim Lemon]

Hi Thomas,
Be aware that if you are attempting to calculate "birthday age", it is
probably better to do it like this:

bdage<-function(dob,now) {
 dobbits<-as.numeric(unlist(strsplit(dob,"/")))
 nowbits<-as.numeric(unlist(strsplit(now,"/")))
 return(nowbits[3]-dobbits[3]-
  (nowbits[2]<dobbits[2] || (nowbits[2]==dobbits[2] && nowbits[1]<dobbits[1])))
}
bdage("20/09/1945","5/8/2016")

You can also do this with date objects, just add the appropriate
format arguments.

Jim


Jim

On Fri, Aug 5, 2016 at 6:35 AM, William Dunlap via R-help
<r-help at r-project.org> wrote:
> difftime objects do not accept 'years' as a value for 'units', so you have
> to change it to numeric.
>
>     as.numeric(age_days, units="days") / 365.242
>
> The units="days" is not needed since you specified it in the call
> to difftime, but it needs to be in one of those places.
>
> Bill Dunlap
> TIBCO Software
> wdunlap tibco.com
>
> On Thu, Aug 4, 2016 at 11:05 AM, Thomas Subia via R-help <
> r-help at r-project.org> wrote:
>
>> Colleagues,
>>
>> age_days <- difftime(Date,DOM,units="days")
>> date_vals$age_yrs <-  age_days/365.242
>>
>> I'm trying to calculate the number of years between DOM and Date.
>> The output reads
>>
>>              DOM               Date                 age_yrs
>> 1 2005-04-04   2015-05-13           10.10563 days
>>
>> How does one not output days?
>>
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>
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>
> ______________________________________________
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> and provide commented, minimal, self-contained, reproducible code.