[R] difference between 2 dates: IN MONTHS the way Motherscompute it

[Francisco J. Zagmutt]

Right!  I updated zoo and the example worked.  I should have started by 
updating the library in the first place...I slept well and I had my cup of 
coffee this morning so I don't really have any excuse :-)

Thanks Gabor!

Francisco


>From: "Gabor Grothendieck" <ggrothendieck at gmail.com>
>To: "Francisco J. Zagmutt" <gerifalte28 at hotmail.com>
>CC: pzs6 at cdc.gov, r-help at stat.math.ethz.ch
>Subject: Re: [R] difference between 2 dates: IN MONTHS the way 
>Motherscompute it
>Date: Sun, 12 Mar 2006 21:13:50 -0500
>
>Maybe you have an old version of zoo?  When I run the first one
>I get 1.  I am using R 2.2.1 under Windows XP and checking
>the Built: line of library(help = zoo) I am using the verson of
>zoo version built on Feb 6, 2006:
>
> > 12*as.numeric(as.yearmon("2006-03-07")-as.yearmon("2006-02-07"))
>[1] 1
>
>In the second example you are not giving it a date but are subtracting
>a bunch of numbers and giving that to as.yearmon.
>
>
>On 3/12/06, Francisco J. Zagmutt <gerifalte28 at hotmail.com> wrote:
> > Thanks Gabor, that's what I understood but then why do I get these 
>results?
> >
> > library(zoo)
> >
> > 12*as.numeric(as.yearmon("2006-03-07")-as.yearmon("2006-02-07"))
> > [1] NA
> > Warning messages:
> > 1: NAs introduced by coercion
> > 2: NAs introduced by coercion
> >
> > 12*as.numeric(as.yearmon(2006-03-07)-as.yearmon(2006-02-07))
> > [1] -12
> >
> > 
>12*as.numeric(as.yearmon(as.Date("2006-03-07"))-as.yearmon(as.Date("2006-02-07")))
> > [1] 1
> >
> > version
> >         _
> > platform i386-pc-mingw32
> > arch     i386
> > os       mingw32
> > system   i386, mingw32
> > status
> > major    2
> > minor    2.1
> > year     2005
> > month    12
> > day      20
> > svn rev  36812
> > language R
> >
> > I am sure I am missing somehting, but what is it??
> >
> > Thanks
> >
> > Francisco
> >
> >
> > >From: "Gabor Grothendieck" <ggrothendieck at gmail.com>
> > >To: "Francisco J. Zagmutt" <gerifalte28 at hotmail.com>
> > >CC: pzs6 at cdc.gov, r-help at stat.math.ethz.ch
> > >Subject: Re: [R] difference between 2 dates: IN MONTHS the way
> > >Motherscompute it
> > >Date: Fri, 10 Mar 2006 21:01:55 -0500
> > >
> > >as.yearmon has a character method so its not necessary to
> > >convert it to Date first:
> > >
> > > > print(as.yearmon.character)
> > >function (x, ...)
> > >as.yearmon(as.Date(x, ...))
> > >
> > >On 3/10/06, Francisco J. Zagmutt <gerifalte28 at hotmail.com> wrote:
> > > > Gabor, please correct me if I am wrong but shouldn't you use as.Date 
>to
> > > > change the date string to a "Date" class before you call as.yearmon?
> > >i.e.
> > > >
> > > > 12*
> > > >
> > 
> >as.numeric(as.yearmon(as.Date("2006-03-07"))-as.yearmon(as.Date("2006-02-07")))
> > > >
> > > > That returns 1 in Windows XP
> > > >
> > > > Regards
> > > >
> > > > Francisco
> > > >
> > > >
> > > >
> > > > >From: "Gabor Grothendieck" <ggrothendieck at gmail.com>
> > > > >To: "Smith, Phil" <pzs6 at cdc.gov>
> > > > >CC: r-help at stat.math.ethz.ch
> > > > >Subject: Re: [R] difference between 2 dates: IN MONTHS the way
> > > > >Motherscompute it
> > > > >Date: Fri, 10 Mar 2006 13:38:12 -0500
> > > > >
> > > > >zoo has the "yearmon" class which will convert a date to a year +
> > > > >0/12 to 11/12 to represent the month, disregarding the day, so:
> > > > >
> > > > >library(zoo)
> > > > >12 * as.numeric((as.yearmon("2006-03-07") - 
>as.yearmon("2006-02-06")))
> > ># 1
> > > > >
> > > > >On 3/10/06, Smith, Phil <pzs6 at cdc.gov> wrote:
> > > > > > Hi R-people:
> > > > > >
> > > > > > I need a function to compute the number of months between 2 
>dates,
> > >in
> > > > >the same way a mother would do it.
> > > > > >
> > > > > > For example, if a kid is born on February 6, the number of 
>months
> > > > >between that date and March 7 is exactly 1 month, although it is 
>only
> > >29
> > > > >days.
> > > > > >
> > > > > > Thank you!
> > > > > > Phil Smith
> > > > > > CDC
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >        [[alternative HTML version deleted]]
> > > > > >
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