[R] colClasses = "Date" in read.delim, how to pass date-format?

[Christoph Lehmann]

so what do you recommend: I just need to be able to sort a data.frame
according to the date entry, and e.g. compute differences between subsequent
dates. Shall I stay with dates (thanks for the hint about confusion of Date
and dates) or is there a better way for this kind of task?

thanks a lot
Cheers
Christoph
> You are confusing class "Date" (part of R) with class "dates" (part of 
> package chron).  There is no as() method for class "dates", so you can't 
> do this.  You can read the column as character (not factor) and convert 
> later, but it sounds like the `huge amount of memory (and time)' is in 
> fact taken by package chron.
> 
> On Mon, 18 Apr 2005, Christoph Lehmann wrote:
> 
> > I have a huge data-set with one column being of type date.
> > Of course I can import the data using this column as "factor" and then 
> > convert it later to dates, using:
> >
> > sws.bezuege$FaktDat <- dates(as.character(sws.bezuege$FaktDat),
> >                             format = c(dates = "d.m.y"))
> >
> >
> > But the conversion requires a huge amount of memory (and time),
> therefore I 
> > would like to use colClasses = c("Date"). My question is:
> > since I have format  = c(dates = "d.m.y"), how can I pass this option to
> > read.delim(..., colClasses = c("Date")) ?
> 
> -- 
> 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
> 

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