[R] interpreting date-related error message

[Phil Spector]

Toby -
     Since dat$doy is just a number, the default S3 method
for format is used, where the second argument is the trim
parameter.  I suspect you are confusing format (which is for
output) with strptime (which is for input).
      For example,

strptime(dat$doy,'%j')

will assume that the dates are in the current year, and 
return a POSIXlt object.  Alternatively, you could pass
an origin to as.Date:

as.Date(dat$doy,origin='2009-12-31')

to get a similar Date object.

                                          - Phil


On Fri, 27 Aug 2010, Toby Gass wrote:

> Hello, helpeRs,
>
> I have a vector of numbers from 1-365 (days of the year) that I would
> like to convert to a date.  There are no NA's and no missing values.
> I did not insert leading zero's for numbers less than 100.
>
> Using the syntax:
>
> dat$doy.1 <- as.numeric(format(dat$doy, "%j" ))
>
> I get the following error message:
>
> Error in prettyNum(.Internal(format(x, trim, digits, nsmall, width,
> 3L,  :
>  invalid 'trim' argument
>
> .What is the error message telling me?
> (Windows OS and R 2.11.1)
>
>
> Thank you.
>
> Toby
>
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