[R] Date variable error

[Ben Bolker]

 <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

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

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

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