To clarify.

Lets turn a date into an age. Given 05/29/1971 in mm/dd/yyyy
format. What is the year difference between then and today?
This would be the "age" requested that starts 05/29/1971 as
one.

Thanks,
Jim




David Winsemius wrote:
>
> 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@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@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@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@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@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
>
> ______________________________________________
> R-help@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.
>
>


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