[R] Date variable error

Ben Bolker bbolker at gmail.com
Tue Dec 14 17:11:49 CET 2010

 <Kurt_Helf <at> nps.gov> writes:

> Greetings
>      In attempting to create a date variable based on month (e.g.,
> February, April, etc.) and year (e.g., 2006) data, wherein I converted
> Month to a factor with Jan=1...Dec=12, I used the following command:
> data$Date<-mdy.date(month=data$Month,day=15,year=data$Year)
> however, I get a message "Error: trunc not meaningful for factors"

  Have you tried


 (I like with() or transform() for making these cleaner:

data <- transform(data,Date=mdy.date(month=as.numeric(Month),day=15,year=Year))

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