R help - Apr 2008 - Error in fromchar(as.character(x)) : character string is not in a standard unambiguous format

Hello,

I was hoping for advice regarding resolving the above error.

I have a csv file that contains the following variable:

  $ Order.Made.Date       : Factor w/ 299 levels 
"1-Apr-08","1-Aug-05",..: 278 285 91 286 159 132 108 261 282
147 ...


I want to calculate a variable named F.length, which is today's date 
minus  the values contained in  the variable: April$Order.Made.Date)
I tried altering the date format but continued to receive the same error.

  > F.length <- difftime ("11/04/2008", April$Order.Made.Date)
 > Error in fromchar(as.character(x)) :   character string is not in 
a standard unambiguous format

  > Order.date <- as.Date (April$Order.Made.Date)
  > Error in fromchar(x) :   character string is not in a standard 
unambiguous format
 > Order.date <- 'as.POSIXlt' (April$Order.Made.Date)
Error in fromchar(as.character(x)) :   character string is not in a 
standard unambiguous format

Any suggestions are appreciated,

Bob

You need to give the format -- '1-Apr-08' might mean 2008-04-01 or 
2001-04-08, and R refuses to guess.

Please *do* read the help file (e.g. as.Date) before posting: the 
international standard format is 2008-04-11, and Australia has adopted 
that standard.

On Fri, 11 Apr 2008, Bob Green wrote:
> Hello,
>
> I was hoping for advice regarding resolving the above error.
Telling R what you intend is the usual way to resolve user errors caused 
by ambiguous input.
>
> I have a csv file that contains the following variable:
>
>  $ Order.Made.Date       : Factor w/ 299 levels
> "1-Apr-08","1-Aug-05",..: 278 285 91 286 159 132 108
261 282 147 ...
>
>
> I want to calculate a variable named F.length, which is today's date
> minus  the values contained in  the variable: April$Order.Made.Date)
> I tried altering the date format but continued to receive the same error.
>
>  > F.length <- difftime ("11/04/2008",
April$Order.Made.Date)
> > Error in fromchar(as.character(x)) :   character string is not in
> a standard unambiguous format
>
>  > Order.date <- as.Date (April$Order.Made.Date)
>  > Error in fromchar(x) :   character string is not in a standard
> unambiguous format
> > Order.date <- 'as.POSIXlt' (April$Order.Made.Date)
> Error in fromchar(as.character(x)) :   character string is not in a
> standard unambiguous format
>
> Any suggestions are appreciated,
>
> Bob

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595