[R] Turn dates into age

[David Winsemius]

On Nov 8, 2009, at 3:11 PM, frenchcr wrote:

>
>
> why do you use 365.25?
>

As opposed to what?

--  
David
>
> dates<-as.character(data[,"date_commissioned"]); # convert dates to
> characters
> #dates[1:10]
> #[1] "19910101" "19860101" "19910101" "19860101" "19910101" "19910101"
> "19910101" "19910101" "19910101" "19910101"
>
> dateObs <- as.Date(dates,format="%Y%m%d")
> #dateObs[1:10]
> #[1] "1991-01-01" "1986-01-01" "1991-01-01" "1986-01-01" "1991-01-01"
> "1991-01-01" "1991-01-01" "1991-01-01" "1991-01-01" "1991-01-01"
>
> today <- Sys.Date()
> x.date <- as.Date(dateObs, format="%Y%m%d")
>
> AGE <- round(as.vector(difftime(today , x.date, units='day') /  
> 365.25))
>
>
>
>
>
> frenchcr wrote:
>>
>>
>> it sure does thank you!
>>
>>
>>> will this work for you
>>>
>>> x <- c('19910101', '19950302', '20010502')
>>> today <- Sys.Date()
>>> x.date <- as.Date(x, format="%Y%m%d")
>>> round(as.vector(difftime(today , x.date, units='day') / 365.25))
>> [1] 19 15  9
>>>
>>
>>
>> On Sun, Nov 8, 2009 at 2:44 PM,  <frenchcr at btinternet.com> wrote:
>>> Hi Jim,
>>>
>>> Thanks for the quick reply...not sure what you mean by frame of
>>> reference(only been using R for 4 days)...to clarify, i need to  
>>> turn my
>>> dates from 1999-10-01 into 1999 then i subtract 2009 -1999 to get  
>>> an age
>>> of 10. The column im working on has 312,000 rows and some have NA  
>>> in them
>>> as we have no dates for that item.
>>>
>>> To recap, the column is just a bunch of dates with some field  
>>> empty, i
>>> want to change the column from "date of commision" to "age of asset"
>>>
>>> Cheers
>>> Chris.
>>
>>
>>
>>
>> jholtman wrote:
>>>
>>> What is the frame of reference to determine the age?   Check out
>>> 'difftime'.
>>>
>>> On Sun, Nov 8, 2009 at 1:50 PM, frenchcr <frenchcr at btinternet.com>  
>>> wrote:
>>>>
>>>> Ive got a big column of dates (also some fields dont have a date  
>>>> so they
>>>> have
>>>> NA instead),
>>>> that i have converted into date format as so...
>>>>
>>>>
>>>> dates<-as.character(data[,"date_commissioned"]); # converted  
>>>> dates to
>>>> characters
>>>> dates[1:10]
>>>> [1] "19910101" "19860101" "19910101" "19860101" "19910101"  
>>>> "19910101"
>>>> "19910101" "19910101" "19910101" "19910101"
>>>>
>>>> dateObs <- as.Date(dates,format="%Y%m%d")
>>>> dateObs[1:10]
>>>> [1] "1991-01-01" "1986-01-01" "1991-01-01" "1986-01-01"  
>>>> "1991-01-01"
>>>> "1991-01-01" "1991-01-01" "1991-01-01" "1991-01-01" "1991-01-01"
>>>>
>>>>
>>>>
>>>> Now i need to turn the dates into AGE, how do i do it? Im not  
>>>> worried
>>>> about
>>>> fractions of years, whole years would do.
>>>>
>>>>
>>>> --
>>>> View this message in context:
>>>> http://old.nabble.com/Turn-dates-into-age-tp26256656p26256656.html
>>>> Sent from the R help mailing list archive at Nabble.com.
>>>>
>>>> ______________________________________________
>>>> R-help at r-project.org mailing list
>>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>>> PLEASE do read the posting guide
>>>> http://www.R-project.org/posting-guide.html
>>>> and provide commented, minimal, self-contained, reproducible code.
>>>>
>>>
>>>
>>>
>>> -- 
>>> Jim Holtman
>>> Cincinnati, OH
>>> +1 513 646 9390
>>>
>>> What is the problem that you are trying to solve?
>>>
>>> ______________________________________________
>>> R-help at r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>> PLEASE do read the posting guide
>>> http://www.R-project.org/posting-guide.html
>>> and provide commented, minimal, self-contained, reproducible code.
>>>
>>>
>>
>>
>
> -- 
> View this message in context: http://old.nabble.com/Turn-dates-into-age-tp26256656p26257435.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> 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
Heritage Laboratories
West Hartford, CT