[R] Calculate difference between dates in years

[Wayne.W.Jones at shell.com]

look at the as.Date function

e.g.

as.Date("2007-04-21")- as.Date("2000-04-21")


also look at the chron library. 

Regards

Wayne


-----Original Message-----
From: r-help-bounces at r-project.org
[mailto:r-help-bounces at r-project.org]On Behalf Of Daniel Brewer
Sent: 24 September 2007 11:23
To: r-help at stat.math.ethz.ch
Subject: [R] Calculate difference between dates in years


Hello,

I would like to be able to calculate the age of someone at a particular
date.  Both dates are date objects.  Here is what I have come up with:

floor(as.numeric(sampleInfo$Date.of.DIAGNOSIS-sampleInfo$Date.of.birth)/365.25)

Is this the best approach? or is there an inbuilt function?  I have
looked at difftime but that does not seem to allow output in years.

Many thanks

Dan

-- 
**************************************************************
Daniel Brewer, Ph.D.
Institute of Cancer Research
Email: daniel.brewer at icr.ac.uk
**************************************************************

The Institute of Cancer Research: Royal Cancer Hospital, a charitable Company Limited by Guarantee, Registered in England under Company No. 534147 with its Registered Office at 123 Old Brompton Road, London SW7 3RP.

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