R help - Jun 2006 - timediff

Hello,

 

I've got 2 dates like these :

 

"2006-02-08 17:12:55"

"2006-02-08 17:15:26"

 

 

I wish to get the middle of these two date :

 

"2006-02-08 17 :14 :10"

 

Is there is a function in R to do that ?

 

Thks all

guillaume


	[[alternative HTML version deleted]]

"COMTE Guillaume" <g.comte at alliance-ir.net> writes:
> I've got 2 dates like these :
> "2006-02-08 17:12:55"
> "2006-02-08 17:15:26"
> I wish to get the middle of these two date :
> "2006-02-08 17 :14 :10"
> Is there is a function in R to do that ?
Well, 
> x1 <- as.POSIXct("2006-02-08 17:12:55")
> x2 <- as.POSIXct("2006-02-08 17:15:26")
> x2-x1
Time difference of 2.516667 mins
> (x2-x1)/2
Time difference of 1.258333 mins
> x1+60*as.numeric((x2-x1)/2)
[1] "2006-02-08 17:14:10 CET"

However, this goes wrong (although not without warning):
> x1+(x2-x1)/2
[1] "2006-02-08 17:12:56 CET"
Warning message:
Incompatible methods ("+.POSIXt", "Ops.difftime") for
"+"

---for reasons that are related to this:
> as.numeric(x2)-as.numeric(x1) # seconds!
[1] 151
> as.numeric(x2-x1) # minutes
[1] 2.516667

(This suggests to me that the methodology for difftime objects is
still not quite complete. Volunteers?)

-- 
   O__  ---- Peter Dalgaard             ?ster Farimagsgade 5, Entr.B
  c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
 (*) \(*) -- University of Copenhagen   Denmark          Ph:  (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)                  FAX: (+45) 35327907

On Tue, 20 Jun 2006 12:38:11 +0200 COMTE Guillaume wrote:
>  
> 
> Hello,
> 
>  
> 
> I've got 2 dates like these :
> 
>  
> 
> "2006-02-08 17:12:55"
> 
> "2006-02-08 17:15:26"
> 
>  
> 
>  
> 
> I wish to get the middle of these two date :
There is a mean method for "POSIXct" objects:

  x <- as.POSIXct(c("2006-02-08 17:12:55", "2006-02-08
17:15:26"))
  mean(x)

Best,
Z
>  
> 
> "2006-02-08 17 :14 :10"
> 
>  
> 
> Is there is a function in R to do that ?
> 
>  
> 
> Thks all
> 
> guillaume
> 
> 
> 	[[alternative HTML version deleted]]
> 
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