R help - Apr 2005 - colClasses = "Date" in read.delim, how to pass date-format?

On 4/18/05, Christoph Lehmann <christoph.lehmann at gmx.ch>
wrote:
> Hi
> 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")) ?
> 
Check out:

http://tolstoy.newcastle.edu.au/R/help/05/02/12003.html

Hi
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")) ?

thanks for a hint

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