R help - Jun 2012 - Day or Month difference between dates???

HI, R-Users:

I got a questions. have been struggling so long time....

I have this data:
> m1$Year_Month
  201009 201010 201011 201101 201102
> min(m1$Year_Month)
  201009

I want to calculate the following two answers, how do I program it?
> difference in Month?????
 [1] 0 1 2 4 5 
>difference in Days?????
 0  31  61 ....

Thank you in advance!!!

Tammy
 		 	   		  
	[[alternative HTML version deleted]]

Hi Tammy,
I suspect that the first 4 digits compose the year, so with

Year_Month<-c(2010*100+9:11,2011*100+1:2)
#check composition
Year_Month

ym<-(Year_Month%/%100*12+Year_Month%%100)
ym-ym[1]

should give the difference in months.

Differences in Days are a bit trickier, since not all months have an
equal number of days. Something like

xd<-as.Date(paste(Year_Month%/%100,Year_Month%%100,"01",sep="-"))
xd-xd[1]

deals with that.

Cheers


Am 01.06.2012 13:31, schrieb Tammy Ma:
> 
> HI, R-Users:
> 
> I got a questions. have been struggling so long time....
> 
> I have this data:
> 
>> m1$Year_Month
>   201009 201010 201011 201101 201102
>> min(m1$Year_Month)
>   201009
> 
> I want to calculate the following two answers, how do I program it?
> 
>> difference in Month?????
>  [1] 0 1 2 4 5 
> 
>> difference in Days?????
>  0  31  61 ....
> 
> Thank you in advance!!!
> 
> Tammy
>  		 	   		  
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
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> 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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Alexander Kirstein, Joachim Pr?l?, Prof. Dr. Dr. Uwe Koch-Gromus

Hello,

Try

library(zoo) # needed for as.yearmon

x <- c(201009, 201010, 201011, 201101, 201102)
(y <- as.Date(paste(x, "01", sep=""),
format="%Y%m%d"))
y - y[1]
12*(as.yearmon(y) - as.yearmon(y[1]))

Note that to have a time difference between dates we need days (paste).

Hope this helps,

Rui Barradas

Em 01-06-2012 12:31, Tammy Ma escreveu:
> HI, R-Users:
>
> I got a questions. have been struggling so long time....
>
> I have this data:
>
>> m1$Year_Month
>    201009 201010 201011 201101 201102
>> min(m1$Year_Month)
>    201009
>
> I want to calculate the following two answers, how do I program it?
>
>> difference in Month?????
>   [1] 0 1 2 4 5
>
>> difference in Days?????
>   0  31  61 ....
>
> Thank you in advance!!!
>
> Tammy
>   		 	   		
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
> 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.