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

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")) ?

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")) ?

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

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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