[R] Mean of difftime vectors : "code infelicity" or intended behaviour ?
charpent at bacbuc.dyndns.org
Tue Mar 17 07:53:20 CET 2009
"+" (and "-") being defined for difftime class, I expected mean() to
return something sensible. This is only half-true :
> mean(c(1:5, 5:1),na.rm=TRUE)
> mean(as.difftime(c(1:5, 5:1),unit="mins"),na.rm=TRUE)
Time difference of 3 mins
Fine so far. However :
> mean(c(1:5, NA,5:1),na.rm=TRUE)
> mean(as.difftime(c(1:5, NA,5:1),unit="mins"),na.rm=TRUE)
Time difference of NA mins
Curiously, var(), max() and min() behave as expected. What's so special
with mean() ?
> RSiteSearch("mean difftime")
[ ... doesn't return anything relevant ]
NB : this isn't done for the hell of it. I intended to replace some
missing dates, with something computed from other dates and mean time
Any thoughs ?
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