[R] Day or Month difference between dates???

[Eik Vettorazzi]

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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Eik Vettorazzi

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